(4x+5)*(4x-5)=231

Solution for (4x+5)*(4x-5)=231 equation:

Simplifying
(4x + 5)(4x + -5) = 231

Reorder the terms:
(5 + 4x)(4x + -5) = 231

Reorder the terms:
(5 + 4x)(-5 + 4x) = 231

Multiply (5 + 4x) * (-5 + 4x)
(5(-5 + 4x) + 4x * (-5 + 4x)) = 231
((-5 * 5 + 4x * 5) + 4x * (-5 + 4x)) = 231
((-25 + 20x) + 4x * (-5 + 4x)) = 231
(-25 + 20x + (-5 * 4x + 4x * 4x)) = 231
(-25 + 20x + (-20x + 16x2)) = 231

Combine like terms: 20x + -20x = 0
(-25 + 0 + 16x2) = 231
(-25 + 16x2) = 231

Solving
-25 + 16x2 = 231

Solving for variable 'x'.

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

Add '25' to each side of the equation.
-25 + 25 + 16x2 = 231 + 25

Combine like terms: -25 + 25 = 0
0 + 16x2 = 231 + 25
16x2 = 231 + 25

Combine like terms: 231 + 25 = 256
16x2 = 256

Divide each side by '16'.
x2 = 16

Simplifying
x2 = 16

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