Question

How do I determine if these two lines are perpendicular?
y=2x-9
3y=5-x

Answer 1

First set em up as y=mx+b

Answer 2

change the bottom one to y = mx+b form

so 3y = 5-x
y = -1/3x + 5/3

compare the m's in each equation.

the m in the first one is 2, and the m in the second one is -1/3

for the lines to be perpendicular, the slopes must be negative inverses of each other...the negative inverse of 2 is -1/2, which is NOT -1/3 so they aren't.

Answer 3

Thank you for the explanation.

Answer 4

no problem!