(2x-4)(2x+4)=84

Solution for (2x-4)(2x+4)=84 equation:

Simplifying
(2x + -4)(2x + 4) = 84

Reorder the terms:
(-4 + 2x)(2x + 4) = 84

Reorder the terms:
(-4 + 2x)(4 + 2x) = 84

Multiply (-4 + 2x) * (4 + 2x)
(-4(4 + 2x) + 2x * (4 + 2x)) = 84
((4 * -4 + 2x * -4) + 2x * (4 + 2x)) = 84
((-16 + -8x) + 2x * (4 + 2x)) = 84
(-16 + -8x + (4 * 2x + 2x * 2x)) = 84
(-16 + -8x + (8x + 4x2)) = 84

Combine like terms: -8x + 8x = 0
(-16 + 0 + 4x2) = 84
(-16 + 4x2) = 84

Solving
-16 + 4x2 = 84

Solving for variable 'x'.

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

Add '16' to each side of the equation.
-16 + 16 + 4x2 = 84 + 16

Combine like terms: -16 + 16 = 0
0 + 4x2 = 84 + 16
4x2 = 84 + 16

Combine like terms: 84 + 16 = 100
4x2 = 100

Divide each side by '4'.
x2 = 25

Simplifying
x2 = 25

Take the square root of each side:
x = {-5, 5}