The graphs of 2y + x + 3 = 0 and 8y + ax + 2 = 0 are perpendicular. Solve for a.
+128472 If they are perpendicular,they have negative reciprocal slopes....so....
Put in form y = mx + b
2 y + x + 3 = 0 8y + ax + 2 = 0
2y = -x - 3 8y = -ax - 2
divide through by 2 divide through by 8
y = (-1/2)x - 3/2 y= -(a)/8 - 1/4
We can solve this
(-1/2) * ( -a/8) = -1
(1/16) a = -1 multiply both sides by 16
a = -16
