(r-4)(r+4)=0

Solution for (r-4)(r+4)=0 equation:

Simplifying
(r + -4)(r + 4) = 0

Reorder the terms:
(-4 + r)(r + 4) = 0

Reorder the terms:
(-4 + r)(4 + r) = 0

Multiply (-4 + r) * (4 + r)
(-4(4 + r) + r(4 + r)) = 0
((4 * -4 + r * -4) + r(4 + r)) = 0
((-16 + -4r) + r(4 + r)) = 0
(-16 + -4r + (4 * r + r * r)) = 0
(-16 + -4r + (4r + r2)) = 0

Combine like terms: -4r + 4r = 0
(-16 + 0 + r2) = 0
(-16 + r2) = 0

Solving
-16 + r2 = 0

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '16' to each side of the equation.
-16 + 16 + r2 = 0 + 16

Combine like terms: -16 + 16 = 0
0 + r2 = 0 + 16
r2 = 0 + 16

Combine like terms: 0 + 16 = 16
r2 = 16

Simplifying
r2 = 16

Take the square root of each side:
r = {-4, 4}