Question

For these questions find the x- and y- intercept.

1. -10x+5y=40
a. x-intercept is 5; y-intercept is -10
b. x-intercept is 8; y-intercept is -4
c. x-intercept is -10; y-intercept is 5
d. x-intercept is -4; y-intercept is 5

2. 5x+4y=80
a. x-intercept is 4; y-intercept is 5
b. x-intercept is 20; y-intercept is 16
c. x-intercept is 5; y-intercept is 4
d. x-intercept is 16; y-intercept is 20

Please help, I don't understand these.

Answer 1

Background: you find an x-intercept when you set y to be zero and you get the y-intercept when you set x to be zero. In a graph this is the point of the equation that passes through the X and Y axis. ( I will do question number 1 and I will let you try question number 2 )

1. -10x + 5y = 40
to find x-intercept set y=0
= -10x + 5(0) = 40 since 5(0) = 0
= -10x = 40 divide both sides by -10 to find X
=> x = 40/-10 = -4
=> the x-intercept for the above equation is -4

to find y-intercept set x = 0
= -10(0) + 5y = 40 since -10(0) = 0
= 0 + 5y = 40
=> 5y = 40 divide both sides by 5 to get the value of Y
=> y = 40/5 = 8
=> the y-intercept for the above equation is 8