Question

Select the pair of equations whose graphs are perpendicular.

2x – 8y = 9
12x – 3y = 7

3x + 6y = 8
y = 2x – 8

y = 2x – 7
x + y = 3

2y = –3x + 5
2x + 3y = 4

Answer 1

The slopes of perpendicular lines have a product of negative one.

Answer 2

Firstly put eq in y = mx+c form

m = slope

for a line to be perpendicular m(perpendicular) = 1/(-m) of the given line

Answer 3

3x + 6y = 8 --> 6y = 8 -3x, slope is -3/6 = -1/2*

y = 2x – 8 --> slope is 2/1

Question: What is the product of (-1/2) * (2/1) ?

@CrazyCountryGirl

Answer 4

@Directrix -1

Answer 5

Yes, so using the theorem that the product of the slopes of perpendicular lines is -1, provided neither line is horizontal or vertical, you can deduce that these two lines of the second option are perpendicular. As shown, the slopes of these two lines have a product of -1. @CrazyCountryGirl

3x + 6y = 8
y = 2x – 8