Which of the following pairs of slopes are of perpendicular lines?

1/2 and 2
3/4 and -4/3
-2/5 and -5/2

Perpendicular lines have negative reciprocal slopes.

To find the negative reciprocal of a number, u flip the number and change the sign.

Example : -3/1 and 1/3 are perpendicular...notice that if I flip -3/1 making it -1/3...and then change the sign1/3...these are negative reciprocals.

1/2 and 2if u flip 1/2 making it 2/1...and change the sign...making it -2/1...therefore, these r NOT perpendicular...1/2 and -2 would be.

3/4 and -4/3flip and change sign...so 3/4 becomes - 4/3...these r perpendicular.

-2/5 and -5/2flip and change...-2/5 becomes 5/2these r NOT perpendicular...-2/5 and 5/2 would be.