20=(x-3)(x+3)

Solution for 20=(x-3)(x+3) equation:

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

Reorder the terms:
20 = (-3 + x)(x + 3)

Reorder the terms:
20 = (-3 + x)(3 + x)

Multiply (-3 + x) * (3 + x)
20 = (-3(3 + x) + x(3 + x))
20 = ((3 * -3 + x * -3) + x(3 + x))
20 = ((-9 + -3x) + x(3 + x))
20 = (-9 + -3x + (3 * x + x * x))
20 = (-9 + -3x + (3x + x2))

Combine like terms: -3x + 3x = 0
20 = (-9 + 0 + x2)
20 = (-9 + x2)

Solving
20 = -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.
20 + -1x2 = -9 + x2 + -1x2

Combine like terms: x2 + -1x2 = 0
20 + -1x2 = -9 + 0
20 + -1x2 = -9

Add '-20' to each side of the equation.
20 + -20 + -1x2 = -9 + -20

Combine like terms: 20 + -20 = 0
0 + -1x2 = -9 + -20
-1x2 = -9 + -20

Combine like terms: -9 + -20 = -29
-1x2 = -29

Divide each side by '-1'.
x2 = 29

Simplifying
x2 = 29

Take the square root of each side:
x = {-5.385164807, 5.385164807}