65=(x-4)(x+4)

Solution for 65=(x-4)(x+4) equation:

Simplifying
65 = (x + -4)(x + 4)

Reorder the terms:
65 = (-4 + x)(x + 4)

Reorder the terms:
65 = (-4 + x)(4 + x)

Multiply (-4 + x) * (4 + x)
65 = (-4(4 + x) + x(4 + x))
65 = ((4 * -4 + x * -4) + x(4 + x))
65 = ((-16 + -4x) + x(4 + x))
65 = (-16 + -4x + (4 * x + x * x))
65 = (-16 + -4x + (4x + x2))

Combine like terms: -4x + 4x = 0
65 = (-16 + 0 + x2)
65 = (-16 + x2)

Solving
65 = -16 + x2

Solving for variable 'x'.

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

Add '-1x2' to each side of the equation.
65 + -1x2 = -16 + x2 + -1x2

Combine like terms: x2 + -1x2 = 0
65 + -1x2 = -16 + 0
65 + -1x2 = -16

Add '-65' to each side of the equation.
65 + -65 + -1x2 = -16 + -65

Combine like terms: 65 + -65 = 0
0 + -1x2 = -16 + -65
-1x2 = -16 + -65

Combine like terms: -16 + -65 = -81
-1x2 = -81

Divide each side by '-1'.
x2 = 81

Simplifying
x2 = 81

Take the square root of each side:
x = {-9, 9}