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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 1 Bruce Mayer, PE Chabot College Mathematics Bruce Mayer, PE Licensed Electrical & Mechanical Engineer BMayer@ChabotCollege.edu Chabot Mathematics §1.2 Graphs Of Functions
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 2 Bruce Mayer, PE Chabot College Mathematics Review § Any QUESTIONS About §1.1 → Introduction to Functions Any QUESTIONS About HomeWork §1.1 → HW-01 1.1
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 3 Bruce Mayer, PE Chabot College Mathematics §1.2 Learning Goals Review the rectangular coordinate system Graph several functions Study intersections of graphs, the vertical line test, and intercepts Sketch and use graphs of quadratic functions in applications
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 4 Bruce Mayer, PE Chabot College Mathematics Points and Ordered-Pairs To graph, or plot, points we use two perpendicular number lines called axes. The point at which the axes cross is called the origin. Arrows on the axes indicate the positive directions Consider the pair (2, 3). The numbers in such a pair are called the CoOrdinates. The first coordinate, x, in this case is 2 and the second, y, coordinate is 3.
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 5 Bruce Mayer, PE Chabot College Mathematics Plot-Pt using Ordered Pair To plot the point (2, 3) we start at the origin, move horizontally to the 2, move up vertically 3 units, and then make a “dot” x = 2 y = 3 (2, 3)
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 6 Bruce Mayer, PE Chabot College Mathematics Example Plot the point (–4,3) Starting at the origin, we move 4 units in the negative horizontal direction. The second number, 3, is positive, so we move 3 units in the positive vertical direction (up) x = –4;y = 3 4 units left 3 units up
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 7 Bruce Mayer, PE Chabot College Mathematics Example Read XY-Plot Find the coordinates of pts A, B, C, D, E, F, G A B C D E F G Solution: Point A is 5 units to the right of the origin and 3 units above the origin. Its coordinates are (5, 3). The other coordinates are as follows: –B: (−2,4) –C: (−3,−4) –D: (3,−2) –E: (2, 3) –F: (−3,0) –G: (0, 2)
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 8 Bruce Mayer, PE Chabot College Mathematics Tool For XY Graphing Called “ Engineering Computation Pad” Light Green Backgound Tremendous Help with Graphing and Sketching Available in Chabot College Book Store I use it for ALL my Hand-Work Graph on this side!
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 9 Bruce Mayer, PE Chabot College Mathematics XY Quadrants The horizontal and vertical axes divide the plotting plane into four regions, or quadrants Note the Ordinate & Abscissa (Ordinate) (Abscissa)
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 10 Bruce Mayer, PE Chabot College Mathematics The Distance Formula The distance between the points (x 1, y 1 ) and (x 2, y 1 ) on a horizontal line is |x 2 – x 1 |. Similarly, the distance between the points (x 2, y 1 ) and (x 2, y 2 ) on a vertical line is |y 2 – y 1 |.
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 11 Bruce Mayer, PE Chabot College Mathematics Pythagorean Distance Now consider any two points (x 1, y 1 ) and (x 2, y 2 ). These points, along with (x 2, y 1 ), describe a right triangle. The lengths of the legs are |x 2 – x 1 | and |y 2 – y 1 |.
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 12 Bruce Mayer, PE Chabot College Mathematics Pythagorean Distance Find d, the length of the hypotenuse, by using the Pythagorean theorem: d 2 = |x 2 – x 1 | 2 + |y 2 – y 1 | 2 Since the square of a number is the same as the square of its opposite, we can replace the absolute-value signs with parentheses: d 2 = (x 2 – x 1 ) 2 + (y 2 – y 1 ) 2
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 13 Bruce Mayer, PE Chabot College Mathematics Distance Formula Formally The distance d between any two points (x 1, y 1 ) and (x 2, y 2 ) is given by
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 14 Bruce Mayer, PE Chabot College Mathematics Example Find Distance Find Distance Between Pt1 & Pt2 Use Dist Formula Pt-1 Pt-2
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 15 Bruce Mayer, PE Chabot College Mathematics Graphing by Dot Connection “Connecting the Dots” ALWAYS works for plotting any y = f(x) from an eqn The procedure Use Fcn Eqn to make a “T-Table” Properly Construct and Label Graph Plot Ordered-Pairs in T-Table Connect Dots with Straight or Curved Lines T-Table for
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 16 Bruce Mayer, PE Chabot College Mathematics Making Complete Plots 1.Arrows in POSITIVE Direction Only 2.Label x & y axes on POSITIVE ends 3.Mark and label at least one unit on each axis 4.Use a ruler for Axes & Straight-Lines 5.Label significant points or quantities
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 17 Bruce Mayer, PE Chabot College Mathematics Example Graph f(x) = 2x 2 Solution: Make T-Table and Connect-Dots xy(x, y) 0 1 –1 2 –2 0228802288 (0, 0) (1, 2) (–1, 2) (2, 8) (–2, 8) x = 0 is Axis of Symm (0,0) is Vertex
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 18 Bruce Mayer, PE Chabot College Mathematics Plot PieceWise Function: f(x) f(x) f(x) f(x) = |x||x||x||x| ReCalling the Absolute Value Definition can State Function in PieceWise Form Make T-Table from Above Fcn Def What will be the SHAPE of the the Graph of this Function? Class Question: What will be the SHAPE of the the Graph of this Function?
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 19 Bruce Mayer, PE Chabot College Mathematics Example Graph f(x) = |x| Make T-table Plot Points, and Connect Dots
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 20 Bruce Mayer, PE Chabot College Mathematics Graph Intersections How To Find Solutions to the Equality of Functions? Graph Both Functions and Find Intersections –At Intersections x & y are the SAME for both functions, and ANY point on the graph is a “Solution” to Fcn Thus at Intersections BOTH Fcns are Simultaneously Solved
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 21 Bruce Mayer, PE Chabot College Mathematics Graph InterSection Example Consider two Functions: Want to Find solution(s), x s, such that Note that this Equation can NOT Solved exactly; The solutions are irrational Numbers Such “NonAlgebraic” Eqns are Called “Transcendental” Find Solution by Graph Intersection(s)
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 22 Bruce Mayer, PE Chabot College Mathematics Graph InterSection Example Plot Both Functions on Same Graph Find Intersection(s) Read x s from intersection points ≈1.44≈4.97≈7.54
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 23 Bruce Mayer, PE Chabot College Mathematics MSExcel vs Transcendental The “Goal Seek” Command in MicroSoft Excel to Find x s with greater Accuracy Use Excel to Solve the Transcendental Equation Collect Terms on One Side, and use “Goal Seek” to find x that satisfies eqn For the Eqn Above the solutions, x s, are called the “zeros” or “roots” of the “zeroed” eqn
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 24 Bruce Mayer, PE Chabot College Mathematics MSExcel vs Transcendental Use The “Goal Seek” Command in MicroSoft Excel to Find x s with greater Accuracy
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 25 Bruce Mayer, PE Chabot College Mathematics Goal Seek (on Data Tab)
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 26 Bruce Mayer, PE Chabot College Mathematics Goal Seek Results (2 Roots)
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 27 Bruce Mayer, PE Chabot College Mathematics Zeros Graphed by MATLAB >> u = linspace(0, 2.5*pi, 300); >> v = cos_ln(u); >> xZ = [0,8]; yZ = [0, 0]; >> plot(u,v, xZ,yZ, 'LineWidth',3), grid, xlabel('u'), ylabel('v'); >> Z1 = fzero(cos_ln,2) Z1 = 1.4429 >> Z2 = fzero(cos_ln,5) Z2 = 4.9705 >> Z3 = fzero(cos_ln,8) Z3 = 7.5425
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 28 Bruce Mayer, PE Chabot College Mathematics Power Function f(x) = Kx n In the Power Function “n” can be ANY number, positive, negative, rational or Irrational. Some Examples M15PwrFcnGraphs_1306.m
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 29 Bruce Mayer, PE Chabot College Mathematics PolyNomial Function The General PolyNomial Function Where n ≡ a positive integer constant a k ≡ any real number constant n (the largest exponent) is called the DEGREE of the Polynomial
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 30 Bruce Mayer, PE Chabot College Mathematics PolyNomial Function The plot of p(x) is continuous and crosses the X-axis no more than n-times Some Examples M15PloyNomialFcnGraphs_1306.m
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 31 Bruce Mayer, PE Chabot College Mathematics Rational Function A rational function is a function f that is a quotient of two polynomials, that is, Where where p(x) and q(x) are polynomials and where q(x) is not the zero polynomial. The domain of f consists of all inputs x for which q(x) ≠ 0.
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 32 Bruce Mayer, PE Chabot College Mathematics Rational Fcn Examples Note the Asymptotic Behavior
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 33 Bruce Mayer, PE Chabot College Mathematics Graphing & Vertical-Line-Test Test a Reln-Graph to see if the Relation represents a Fcn If no VERTICAL line intersects the graph of a relation at more than one point, then the graph is the graph of a function.
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 34 Bruce Mayer, PE Chabot College Mathematics Example Vertical-Line-Test Use the Vertical Line Test to determine if the graph represents a function SOLUTION NOT a function as the Graph Does not pass the vertical line test
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 35 Bruce Mayer, PE Chabot College Mathematics Example Vertical-Line-Test Use the Vertical Line Test to determine if the graph represents a function SOLUTION NOT a function as the Graph Does not pass the vertical line test TRIPLE Valued
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 36 Bruce Mayer, PE Chabot College Mathematics Example Vertical-Line-Test Use the Vertical Line Test to determine if the graph represents a function SOLUTION IS a function as the Graph Does pass the vertical line test SINGLE Valued SINGLE Valued
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 37 Bruce Mayer, PE Chabot College Mathematics Example Vertical-Line-Test Use the Vertical Line Test to determine if the graph represents a function SOLUTION IS a function as the Graph Does pass the vertical line test SINGLE Valued
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 38 Bruce Mayer, PE Chabot College Mathematics Quadratic Functions All quadratic functions have graphs similar to y = x 2. Such curves are called parabolas. They are U-shaped and symmetric with respect to a vertical line known as the parabola’s line of symmetry or axis of symmetry. For the graph of f(x) = x 2, the y-axis is the axis of symmetry. The point (0, 0) is known as the vertex of this parabola.
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 39 Bruce Mayer, PE Chabot College Mathematics The Vertex of a Parabola The FORMULA for the vertex of a parabola given by f(x) = ax 2 + bx + c: The x-coordinate of the vertex is −b/(2a). The axis of symmetry is x = −b/(2a). The second coordinate of the vertex is most commonly found by computing f(−b/[2a])
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 40 Bruce Mayer, PE Chabot College Mathematics Graphing f(x) = ax 2 + bx + c 1.The graph is a parabola. Identify a, b, and c 2.Determine how the parabola opens If a > 0, the parabola opens up. If a < 0, the parabola opens down 3.Find the vertex (h, k). Use the formula
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 41 Bruce Mayer, PE Chabot College Mathematics Graphing f(x) = ax 2 + bx + c 4.Find the x-intercepts Let y = f(x) = 0. Find x by solving the equation ax 2 + bx + c = 0. If the solutions are real numbers, they are the x-intercepts. If not, the parabola either lies –above the x–axis when a > 0 –below the x–axis when a < 0
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 42 Bruce Mayer, PE Chabot College Mathematics Graphing f(x) = ax 2 + bx + c 5.Find the y-intercept. Let x = 0. The result f(0) = c is the y-intercept. 6.The parabola is symmetric with respect to its axis, x = −b/(2a) Use this symmetry to find additional points. 7.Draw a parabola through the points found in Steps 3-6.
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 43 Bruce Mayer, PE Chabot College Mathematics Example Graph SOLUTION Step 1 a = –2, b = 8, and c = –5 Step 2 a = –2, a < 0, the parabola opens down. Step 3 Find (h, k). Maximum value of y = 3 at x = 2
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 44 Bruce Mayer, PE Chabot College Mathematics Example Graph SOLUTION Step 4 Let f (x) = 0. Step 5 Let x = 0.
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 45 Bruce Mayer, PE Chabot College Mathematics Example Graph SOLUTION Step 6 Axis of symmetry is x = 2. Let x = 1, then the point (1, 1) is on the graph, the symmetric image of (1, 1) with respect to the axis x = 2 is (3, 1). The symmetric image of the y–intercept (0, –5) with respect to the axis x = 2 is (4, –5). Step 7 The parabola passing through the points found in Steps 3–6 is sketched on the next slide.
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 46 Bruce Mayer, PE Chabot College Mathematics Example Graph SOLUTION cont. Sketch Graph Using the points Just Determined
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 47 Bruce Mayer, PE Chabot College Mathematics WhiteBoard Work Problems §1.2-44 Supply & Demand
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 48 Bruce Mayer, PE Chabot College Mathematics All Done for Today AutoMobile Stopping Distance
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 49 Bruce Mayer, PE Chabot College Mathematics Bruce Mayer, PE Licensed Electrical & Mechanical Engineer BMayer@ChabotCollege.edu Chabot Mathematics Appendix –
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 50 Bruce Mayer, PE Chabot College Mathematics
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 51 Bruce Mayer, PE Chabot College Mathematics
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 52 Bruce Mayer, PE Chabot College Mathematics
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 53 Bruce Mayer, PE Chabot College Mathematics (120, 0)
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 54 Bruce Mayer, PE Chabot College Mathematics
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 55 Bruce Mayer, PE Chabot College Mathematics
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 56 Bruce Mayer, PE Chabot College Mathematics
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 57 Bruce Mayer, PE Chabot College Mathematics Graph by MATLAB
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BMayer@ChabotCollege.edu MTH15_Lec-02_Fa13_sec_1-2_Fcn_Graphs.pptx 58 Bruce Mayer, PE Chabot College Mathematics MATLAB Code % Bruce Mayer, PE % MTH-15 23Jun13 % M15P12441306.m % % The FUNCTION p = linspace(0,120,500); E = -p.^2/5 + 24*p; % % the Plot axes; set(gca,'FontSize',12); whitebg([0.8 1 1]); % Chg Plot BackGround to Blue-Green plot(p,E, 'LineWidth', 3),axis([0 120 0 800]),... grid, xlabel('\fontsize{14}p ($/Unit)'), ylabel('\fontsize{14}E ($k/Month)'),... title(['\fontsize{16}MTH15 P1.2-44 Bruce Mayer, PE',]),... annotation('textbox',[.55.055.0.1], 'FitBoxToText', 'on', 'EdgeColor', 'none', 'String', 'M15P12441306.m','FontSize',9)
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