Exercise 39 Page 214

Functions where y varies directly with x, direct variation equations, follow 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= 5, y= 2

2=m( 5)

DivEqn

.LHS /5.=.RHS /5.

2/5=m

RearrangeEqn

Rearrange equation

m=2/5

Now that we have the constant of variation, we can write the function. y=2/5x 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=2.

y=2/5x

Substitute

x= 2

y=2/5( 2)

▼

Multiply

MoveRightFacToNum

a/c* b = a* b/c

y=2* 2/5

Multiply

Multiply

y=4/5

For the equation y= 25x, when x=2, the value of y is 45.