Remediation Notes

Relation Function Every equation/graph/set of ordered pairs represents a relation, but sometimes a relation is a function. Functions are just relations in which the x values of its points (ordered pairs) do not repeat. If a graph passes the vertical line test, then it is the graph of a function.

To determine if a graph is a function, we use the vertical line test. If it passes the vertical line test then it is a function. If it does not pass the vertical line test then it is not a function.

Vertical Line Test: 1.Draw a vertical line through the graph. 2. See how many times the vertical line intersects the graph at any one location. If Only Once – Pass (function) If More than Once – Fail (not function)

Is this graph a function? Yes, this is a function because it passes the vertical line test. Only crosses at one point.

Is this graph a function? No, this is not a function because it does not pass the vertical line test. Crosses at more than one point.

x column To determine if a table represents a function, we look at the x column (domain). once If each number in the x column appears only once in that column, it is a function.

You can use the vertical line test to determine whether a relation is a function. Vertical Line Test If no vertical line intersects a graph in more than one point, the graph represents a function. If some vertical line intercepts a graph in two or more points, the graph does not represent a function. Relations and Functions

y x (-4,3) (2,3) (-1,-2) (0,-4) (3,-3) State the domain and range of the relation shown in the graph. Is the relation a function? The relation is: { (-4, 3), (-1, 2), (0, -4), (2, 3), (3, -3) } The domain is: { -4, -1, 0, 2, 3 } The range is: { -4, -3, -2, 3 } Each member of the domain is paired with exactly one member of the range, so this relation is a function. Relations and Functions

Is this relation a function? Yes, this is a function because each number in the x column only appears once. Every number just appears once. XY

Is this relation a function? No, this is not a function because 10 appears in the x column more than once. XY The number 10 appears more than once.

To Evaluate a Function for f(#): Plug the # given in the (#) into all x’s Simplify Try these…

Functions Remember f(x), g(x), h(x), … all just mean y. We use f(x), g(x), h(x), … when we have more than one y = equation.

Review Evaluate for f(3) = (3) 2 – 2(3) + 5 f(3) = 8 f(-1) = 5(-1) 3 – 2(-1) – 8 f(-1) = -11

©1999 by Design Science, Inc.15 Basic function operations Sum Difference Product Quotient

You MUST DISTRIBUTE the NEGATIVE

You MUST FOIL

If you are given a set of ordered pairs or a graph (which you would find the ordered pairs all by yourself) The x values are the DOMAIN The y values are the RANGE Domain and Range: { (-3,5), (-1, 6), (0, 4), (2, 3.5), (6, 13), (6, 29} Range: { 3.5, 4, 5, 6, 13, 29} Domain: { -3, -1, 0, 2, 6 }

Domain and Range: If the equation is a line (y = mx + b or y = #) DOMAIN AND RANGE ARE ALL REAL NUMBERS ALWAYS!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!

If there is an x in the denominator of a fraction, you need to find the value of x that makes the ENTIRE DENOMINATOR equal zero. This number is the EXCEPTION to the DOMAIN of all real numbers. Domain and Range: Domain is all real numbers except 0 Domain is all real numbers except 5 Domain is all real numbers except -9

If you are given a line segment The DOMAIN (x values) is written like # < x < # The RANGE (y values) is written like # < y < # # < x < # # < y < # Domain and Range:

If you are given a parabola The DOMAIN is ALWAYS ALL REAL NUMBERS The RANGE (y values) is written like y > # or y < # Domain and Range:

Find domain and range from an equation Most of the functions you study in this course will have all real numbers for both the domain and range. We’ll only look at the domain for exceptions: 1. Fractions: cannot have the denominator (bottom) = 0, so domain cannot be any x-value that makes the denominator= 0 Examples Domain: x≠0 Domain: x≠3 (it’s okay for x=0 on top!) Domain: x≠1 or -1 because they both make the denominator=0 Question: How can you calculate which values make the denominator = 0? Set up the equation denominator = 0 and solve it. Those values are NOT allowed!

Review

Domain: {-3,-2,1,3} Domain: Domain: {x| } Range: {0, -3} Range: y=4 or {4} Range: {y| } *Don ’ t repeat y *x is between -2 and 1 *This is “ set notation ” y x ● ● ● ● y x y x Domain: Domain: x is any real # Range: Range: y is any real # *Graph continues rt*Graph continues down *Graph continues all ways Examples

x y x y Does the graph represent a function? Name the domain and range. Yes D: all reals R: all reals Yes D: all reals R: y ≥ -6

x y x y Does the graph represent a function? Name the domain and range. No D: x ≥ 1/2 R: all reals No D: all reals R: all reals

Visit these sites for remediation: alg_tut30b_operations.htm