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Word problems/Function notes absent copy Thurs/Fri 4/11,12.
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Function and its rulesA function is a set of ordered pairs (x,y) so that each x value we pick corresponds to exactly one y value after we solve.Ex: y = 2x + 3 (2,7) 7 = 2(2) + 3 7 = 4 + 3 7 = 7 y = 2x + 9Function ruleoutput = y input = x
Example 1 • A taxi driver charges a flat rate of 2 dollars to ride in a cab. He also charges 1 dollars for every mile that he has to drive. Write an equation that represents a person that travels from 1 to 3 miles in a cab and how much it costs for each ride. Hint: y = total cost and x = the number of miles the taxi drove. y = 1x + 2 • How do we write the equation of a line in slope intercept form? • Y = mx + b • What is the constant (b) that never changes in the word problem? • b = 2 • What is the slope (m) in this word problem. • m = 1 • What input (X) do we have to substitute in to the linear equation in order to find the total cost (output, Y) for each ride? • 1 to 3 can be put in for the input.
Graph example 1 • Show the work from example 1 Below. 1. y = 1(1) + 2 y = 1 + 2 y = 3 (1,3) • Y = 1(2) + 2 y = 2 + 2 y = 4 ( 2,4) • Y = 1(3) + 2 y = 3 + 2 y = 5 ( 3,5)
Example 2 • Shasta pays $1 for a can of dog food each day. She also pays $2 for each cookie she buys. Write an equation that represents Shasta buying 1 to 3 cookies and how much is her total treat fee. y = 2x + 1 • How do we write the equation of a line in slope intercept form? • Y = mx + b • What is the constant (b) that never changes in the word problem? • b = 1 • What is the slope (m) in this word problem. • m = 2 • What input (X) do we have to substitute in to the linear equation in order to find the total cost (output, Y) for each ride? • 1 to 3 cookies is the input
Graph from Example 2 • Show the work from example 2 Below. • 1. y = 2(1) + 1 y = 2 + 1 y = 3 (1,3) • 2. y = 2(2) + 1 y = 4 + 1 y = 5 (2,5) • 3. y = 2(3) + 1 y = 6 + 1 y = 7 (3,7)