Exercise 19 Page 304

Direct variation equations are functions where y varies directly with x. They have a specific format. y= mx In this form, m≠ 0. By substituting the given values for x and y into the equation, we can determine the constant of variation, m.

y=mx

SubstituteII

x= 4, y= 10.4

10.4=m( 4)

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Solve for m

RearrangeEqn

Rearrange equation

m(4)=10.4

DivEqn

.LHS /4.=.RHS /4.

m=10.4/4

UseCalc

Use a calculator

m=2.6

Now that we have the constant of variation, we can write the function. y= 2.6x Finally, we will substitute 12 for x to find the y-value.

y=2.6x

Substitute

x= 12

y=2.6 * ( 12)

Multiply

Multiply

y=31.2

We have found that y=31.2 when x=12.