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 sign ... 1/3 ... these are negative reciprocals.

1/2 and 2 ... if 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 - 4/3 ... flip and change sign ... so 3/4 becomes - 4/3 ... these r perpendicular.

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