Are the lines y = - x - 6 and 3x - 3y = 9 perpendicular? Explain

the lines are perpendicular

Step-by-step explanation:

if they are perpendicular the products of their gradients would be - 1

the gradient of y=-x-6 is - 1

the second equation needs to written to conform to y=mx+c

hence, 3x-3y=9

3x-9=3y

y=3x-9/3=x-3. the gradient of this line is 1

1x-1 = - 1