Which line is perpendicular to y=2x+5?

(A) y=5x+2

(B) y=2x-4

(C) y=1/2x+1

(D) y=-1/2x+5

Y = mx + n

m = Slope

To two lines be perpendicular to each other the slopes need to meet the condition: ma x mb = - 1

y = 2x + 5

ma = 2

D: y = - 1/2x + 5

mb = - 1/2

ma x mb = - 1

2 x - 1/2 = - 1

2/1 x - 1/2 = - 1

-2/2 = - 1

-1 = - 1

It's true.

Answer: D.