Question

The graph of which of the following will be perpendicular to the graph of y=2x-4

A) 2x+y=4
B) 4x-2y=4
C) y=-2x+8
D) 2x+4y=1

Answer 1

Graphs of lines are perpendicular if their lsopes multiply to -1. In this case, since the slope of the line we know is 2, the slope of our line needs to be -1/2. Now we need to find the slopes of each of these choices.

2x + y = 4

y = -2x + 4

Since -2 ≠ -1/2, the answer is not A

4x - 2y = 4

Get positive y by itself

2y = 4x - 4

y = 2x - 2

Since 2 ≠ -1/2, the answer is not B

y = -2x + 8

Since -2 ≠ -1/2, the answer is not A

2x + 4y = 1

Get y by itself

4y = -2x + 1

Get y

y = -1/2x + 1

Since -1/2 = -1/2, the answer is D