I'll give brainliest :) Are the lines y = –x – 4 and 5x + 5y = 20 perpendicular? Explain.

Yes; the product of their slopes is −1.

Yes; their slopes are equal.

No; their slopes are equal.

No; their slopes are not equal

C

Step-by-step explanation:

In the equation y = -x - 4, the gradient is -1.

While in the second equation,

5x + 5y = 20

y = -x + 4

So the gradient is -1 too

Both sides are not perpendicular to each other because if you apply the formula, m1m2 = -1, and if substitute both gradient, (-1)(-1) = 1 ≠ -1

Therefore, no they are not perpendicular but parallel instead.

no not all of them.

step-by-step explanation:

some of them have a square base.