What is the equation in slope-intercept form of the line that passes through the point (-1, -4) and is perpendicular to the graph of the line represented by -X-2y = 0?

Question

A) y= 2x-2

B) y= -1/2x - 9/2

C) y= -2x-6

D) y= 1/2x

Answer 1

Hello Bianca,

If you rewrite -x-2y=0 in slope-intercept form, you will get: -2y=x ---> y = (-1/2)*x

Two perpendicular lines need to satisfy this condition: (slope of line 1) * (slope of line 2) = -1

so (-1/2) * slope 2 = =-1, so slope 2 = -1/(-1/2) = 2.

From there, you can go ahead and choose the (only) answer that has a slope of 2.

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Or, in problems where multiple answers have the correct slope, you could do this:

for your perpendicular line, y = 2x + b

to find b, plug the ordered pair (-1,-4) in that equation: -4 = 2(-1)+b ---> -4 = -2+b ---> b = -2

So your perpendicular equation is y = 2x-2

Cheers