Bethyl28
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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.

Respuesta :

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