Determine whether the lines are parallel, perpendicular, or neither.

Question

y = 9x + 9 and y = -9x + 9

Answer 1

in y = mx + b, the slop is m

for parallel lines the slopes must be the same
for perpendicular lines the slopes are negative reciprocals of each other.

I see the first slope as +9 and the second as -9

so which fits?

Answer 2

perpendicular

Answer 3

no, its neither

to be perpendicular, if one is +9 the other would have to be - 1/9