Question

i'll fan+i'll give medal!!
Select the pair of equations whose graphs are perpendicular.

A. 2x – 8y = 9
12x – 3y = 7

B. 3x + 6y = 8
y = 2x – 8

C. y = 2x – 7
x + y = 3

D. 2y = –3x + 5
2x + 3y = 4

Answer 1

2y = -3x + 5
Gradient = -3/2

2x + 3y = 4
Gradient = -2/3
-1/(-2/3) = -3/-2 = 3/2 not equal to -3/2 so not perpendicular.

Answer 2

First find the standard form of the equations. When you do that, you should get b as your answer.

Answer 3

@smileyxl3 , yours is a good answer, but I think gradient is not suitable for her :). I think the idea of slope is better.

Slope of a line * Slope of the other line = -1

with y = mx + b, slope is m. so @xellaphantx you can find m and answer for yourself

Answer 4

I meant b as in the answer choices.

Answer 5

slope of:3x + 6y = 8

6y = -3x+8
y = (-1/2)x+8/6 (slope is -1/2).

slope of:
y = 2x - 8 (slope is 2)

(-1/2)(2) = -1

this is perpendicular