Exercise 8 Page 177

To determine the x-intercept for the given equation, we will substitute 0 for y and solve for x. To determine the y-intercept, we will substitute 0 for x and solve for y.

Finding the x-intercept

Think of the point where the graph of an equation crosses the x-axis. The y-value of that (x,y) coordinate pair is equal to 0, and the x-value is the x-intercept. Consider the given equation. -3/4x+5/6y=15Let's substitute 0 for y and solve for x.

-3/4x+5/6y=15

Substitute

y= 0

-3/4x+5/6( 0)=15

ZeroPropMult

Zero Property of Multiplication

-3/4x=15

MultEqn

LHS * 4=RHS* 4

-3x=60

DivEqn

.LHS /-3.=.RHS /-3.

x=-20

The x-intercept of the equation is -20.

Finding the y-intercept

In the same way as above, now consider the point where the graph of the equation crosses the y-axis. The x-value of the (x,y) coordinate pair at the y-intercept is 0. Therefore, substituting 0 for x will give us the y-intercept.

-3/4x+5/6y=15

Substitute

x= 0

-3/4( 0)+5/6y=15

ZeroPropMult

Zero Property of Multiplication

5/6y=15

MultEqn

LHS * 6=RHS* 6

5y=90

DivEqn

.LHS /5.=.RHS /5.

y=18

The y-intercept of the equation is 18.