Exercise 82 Page 483

Functions where y varies directly with x, direct variation equations, follow a specific format. y=mx In this form, m≠ 0. We can substitute the given x- and y-values into this equation to determine the constant of variation, m.

y=mx

SubstituteII

x= 2, y= 4

4=m( 2)

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Solve for m

DivEqn

.LHS /2.=.RHS /2.

4/2=m

\CalcQout

2=m

RearrangeEqn

Rearrange equation

m=2

Now that we have the constant of variation, we can write the function. y=2x With this equation, we can find any value of x or y when we are given the other. In this case, we are looking for y when x=5.

y=2x

Substitute

x= 5

y=2( 5)

Multiply

Multiply

y=10

For the equation y=2x, when x=5, the value of y is 10.