The line parallel to 3x+y=0, that has the same x intercept as y=3x-9? How did you get it.

Question

The line parallel to 3x+y=0, that has the same x intercept as y=3x-9? How did you get it. I don't understand how to get my answer properly. Step by Step please

Answer 1

Parallel means same slope.  If you write the equations in slope intercept form y = mx + b then m is the slope.  

 

Your first line is y = -3x which has a slope of -3.  So m = -3 in the answer.  

 

The x intercept is the x value when y = 0.  

 

Your second equation is y = 3x - 9.  If you set y = 0 and solve for the x intercept you get 

 

0 = 3x - 9

3x = 9

x = 3

 

So in your answer of y = -3x + b you want the x intercept to also be 3.  So set y = 0 and x = 3 and solve for b 

 

0 = -3(3) + b

b = 9

 

So your answer is y = -3x + 9