Question

What is the equation of a line that is perpendicular to the line y = - 1/2 x + 1 and passes through the point (8, - 1)? A y = −1/2 x + 8 B y = 2x - 17 C y = −1/2 x − 2 D y = 2x - 1

Answer 1

Answer is B y = 2x - 17

First find the negative reciprocal of the gradient for y = -1/2 x + 1 to find the perpendicular line gradient.

-1/2 = 2

Gradient of perpendicular line = 2

Perpendicular line is y=2x + c

Substitute (8,-1) into the line to find the y-intercept (c).

-1 = 2(8) + c
-1 = 16 + c
c = -17

Therefore, the perpendicular line is y = 2x - 17.