72=(x-3)(x+3)

Solution for 72=(x-3)(x+3) equation:

Simplifying
72 = (x + -3)(x + 3)

Reorder the terms:
72 = (-3 + x)(x + 3)

Reorder the terms:
72 = (-3 + x)(3 + x)

Multiply (-3 + x) * (3 + x)
72 = (-3(3 + x) + x(3 + x))
72 = ((3 * -3 + x * -3) + x(3 + x))
72 = ((-9 + -3x) + x(3 + x))
72 = (-9 + -3x + (3 * x + x * x))
72 = (-9 + -3x + (3x + x2))

Combine like terms: -3x + 3x = 0
72 = (-9 + 0 + x2)
72 = (-9 + x2)

Solving
72 = -9 + 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.
72 + -1x2 = -9 + x2 + -1x2

Combine like terms: x2 + -1x2 = 0
72 + -1x2 = -9 + 0
72 + -1x2 = -9

Add '-72' to each side of the equation.
72 + -72 + -1x2 = -9 + -72

Combine like terms: 72 + -72 = 0
0 + -1x2 = -9 + -72
-1x2 = -9 + -72

Combine like terms: -9 + -72 = -81
-1x2 = -81

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

Simplifying
x2 = 81

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