Fri, 12/15/10 WARM-UP: TO BE COLLECTED! 1.) Find the slope of the following points (2a, 3b) and (5a, 6b) 2.) Dave graphs the functions y = x – 3 and y = 4x + 1 on the same State two ways the graphs are different. set of coordinate axes. Explain the reason for each difference. HW: CATCH UP! REVIEW PAST NOTES, HW, TESTS, QUIZZES, ETC! ~50% of the class is between grades (88%-92%, 78-82%, etc) 1.) b/a 2.) The graph of the line y = x – 3 will cross the y-axis at -3 and the graph of the line of y = 4x + 1 will cross the y-axis at 1. This is because the y-intercept of y = x – 3 is -3 and the y-intercept of y = 4x + 1 is 1. The graph of the line y = x – 3 will be less steep than the graph of the line y = 4x + 1. This is because the slope of the line y = x -3 is 1 and the slope of the line y = 4x + 1 is 4. If the slope is greater, the line is steeper.

Families of linear graphs http://www.glencoe.com/sites/texas/student/mathematics/assets/animation/algebra1/ALG1CIM4-3.swf

SWBAT… Write equations in slope-intercept form Mon, 1/3 Agenda WU (10 min) 3 practice problems to refresh our memories! (10 min) Notes on writing equations of lines (2 examples) (25 min) Start on hw (5 min) WARM-UP: 1. Write the homework in your planner 2. Find the slope of Ax + By = C 3. Solve for y: 5x + 4y = 80 HW#5: Writing Eqns of lines in Slope-Intercept Form 1.) m = -A/B 2.) y = -5/4x + 20

1/3 What is the slope of 5x + 4y = 80 A. m = -5 x B. m = -5 C. m = -4 D. m = - 5 m = -5/4

Which equation(s) has the same y-intercept as y = ½x + 2? 2/3 Which equation(s) has the same y-intercept as y = ½x + 2? A. y = 2x + 4 B. 2 – y = ½x C. y – 2 = x D. y = -2 + 5x b = 2 Answer: B and C

Which equation is parallel to the line -2x + 4y = 3? 3/3 Which equation is parallel to the line -2x + 4y = 3? A. y = -1/2 x + 5 B. y = 2x – 6 C. y = -2x + 4 D. y = ½x – 2 Parallel lines have the SAME slope. Answer: D (m = ½)

Quiz Writing equations of lines Writing equations of lines Monday, 1/3 Tuesday, 1/4 Wednesday, 1/5 Thursday, 1/6 Friday, 1/7 Writing equations of lines Writing equations of lines Quiz Point slope form & Standard form Lines of best fit activity All 3 forms of lines 1. Slope-intercept 2. Point-slope 3. Standard Monday, 1/10 Tuesday, 1/11 Wednesday, 1/12 Thursday, 1/13 Friday, 1/14 Parallel and perpendicular Lines TBD Monday, 1/17 Tuesday, 1/18 Wednesday, 1/19 Thursday, 1/20 Friday, 1/21 MLK NO CLASSES Final review Finals – evens ALGEBRA FINAL Part I Finals – odds ALGEBRA FINAL Part II Monday, 1/24 Tuesday, 1/25 Wednesday, 1/26 Thursday, 1/27 Friday, 1/28 END OF Q2/S1

Quiz Writing equations of lines Writing equations of lines Monday, 1/3 Tuesday, 1/4 Wednesday, 1/5 Thursday, 1/6 Friday, 1/7 Writing equations of lines Writing equations of lines Quiz Point slope form & Standard form Scantron TESTING All 3 forms of lines 1. Slope-intercept 2. Point-slope 3. Standard Monday, 1/10 Tuesday, 1/11 Wednesday, 1/12 Thursday, 1/13 Friday, 1/14 Parallel and perpendicular Lines Infinity teachers project Monday, 1/17 Tuesday, 1/18 Wednesday, 1/19 Thursday, 1/20 Friday, 1/21 MLK NO CLASSES Final review Finals – evens ALGEBRA FINAL Part I Finals – odds ALGEBRA FINAL Part II Monday, 1/24 Tuesday, 1/25 Wednesday, 1/26 Thursday, 1/27 Friday, 1/28 END OF Q2/S1

1. Set-up Cornell notes. Topic is “writing equations of lines in slope-intercept form” 2. Example 1: Write the equation of the line, in slope-intercept form, that passes through (3, 5) and (5, 9) 3. Plot (3, 5) and (5, 9) on a graph paper square and paste in your note book. Using your graph, write the equation of the line.

y = mx + b y = mx+ b is an equation that defines a line A line has two characteristics: 1.) Slope 2.) Points that fall on the line To write the equation of a line, you need: 1.) The slope of the line 2.) ANY point on the line

Ex1: Write the equation of the line, in slope-intercept form, that passes through (3, 5) and (5, 9) m = (y2-y1)/(x2-x1) Step 1: Find the slope m = (9-5)/(5-3) = 4/2 = 2 Step 2: Plug in either coordinate into y = mx + b and solve for b (3, 5) (5, 9) y = mx + b y = mx+b 5 = 2(3) + b OR 9 = 2(5) + b 5 = 6 + b 9 = 10 + b -1 = b -1 = b Step 3: Write the equation of the line by substituting the values you computed for m (step 1) and b (step 2) in y = mx + b y = mx + b y = 2x – 1 Besides (3, 5) and (5, 9), what’s another point on this line? Hint: b=-1 (0, -1)

Ex2: Write the equation of the line, in slope-intercept form, with a slope of 10 that passes through (-1, -4) m = 10 Step 1: Find the slope Step 2: Plug in either coordinate into y = mx + b and solve for b (-1, -4) y = mx + b -4 = 10(-1) + b -4 = -10 + b -6 = b Step 3: Write the equation of the line by substituting the values you computed for m (step 1) and b (step 2) in y = mx + b y = mx + b y = 10x – 6 Besides (-1, 4) what’s another point on this line? (0, -6)

SWBAT… Write equations in slope-intercept form Tues, 1/4 Agenda WU (15 min) Review hw#5 (15 min) Quiz (15 min) WARM-UP: Write the slope-intercept form of an equation of the line that satisfies each condition: 1.) Has slope 3 and y-intercept -5 2.) Passes through (5, -7) and has a slope of 3 3.) Passes through (6, -3) and (12, -3) 4.) Has an x-intercept of -2 and a y-intercept of 4 (Hint: write the two points) 2 problems 1. y = 3x – 5 2. y = 3x – 22 3. y = -3 4. y = 2x + 4 (the two points are (-2, 0) and (0, 4))

HW#5: Answers Y = 5x – 20 Y = 3/4x – 2 Y = 10x + 6 Y = 2/7x - 2 4/7 D B C a: C = 0.06y + 0.30 19. b: $7.26 C x represents the number of tickets per order, y represents the total cost of the order B x represents the numbers of tickets sold, y represents the total amount of money 20. A x represents the number of days, y represents the total depth of water in the pool in inches

Tuesday, 1/4/11: Homework: 1. Consider the points (3, 7), (-6, 1) and (9, p) on the same line. Find the value of p. 2. The x-intercept of a line is p, and the y-intercept is q. Write an equation of the line in slope-intercept form. p = 11 y = -q/p + q