Find the value of k so that the graphs of 8y=kx-4 and 6x+24y=12 are perpendicular.

Kx = 4

/ / Solve equation [1] for the variable x

[1] 6x = 24y - 30 [1] x = 4y - 5

/ / Plug this in for variable x in equation [2]

[2] - 12• (4y-5) - 24y = - 36 [2] - 72y = - 96

/ / Solve equation [2] for the variable y

[2] 72y = 96 [2] y = 4/3

/ / By now we know this much:

x = 4y-5 y = 4/3

/ / Use the y value to solve for x

x = 4 (4/3) - 5 = 1/3 Solution : {x, y} = {1/3,4/3}