Use slopes to determine if the lines 4x-7y=9 and 7x+4y=5 are perpendicular.

Perpendicular.

Step-by-step explanation:

4x - 7y = 9 - --> 7y = 4x - 9 - --> y = 4/7 x - 9/7, slope = 4/7

7x + 4y = 5 - --> 4y = - 7x + 5 - --> y = - 7/4 x + 5/4, slope = - 7/4

lopes are negative-reciprocal, so these lines are perpendicular.