40=(x+3)(x-3)

Solution for 40=(x+3)(x-3) equation:

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

Reorder the terms:
40 = (3 + x)(x + -3)

Reorder the terms:
40 = (3 + x)(-3 + x)

Multiply (3 + x) * (-3 + x)
40 = (3(-3 + x) + x(-3 + x))
40 = ((-3 * 3 + x * 3) + x(-3 + x))
40 = ((-9 + 3x) + x(-3 + x))
40 = (-9 + 3x + (-3 * x + x * x))
40 = (-9 + 3x + (-3x + x2))

Combine like terms: 3x + -3x = 0
40 = (-9 + 0 + x2)
40 = (-9 + x2)

Solving
40 = -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.
40 + -1x2 = -9 + x2 + -1x2

Combine like terms: x2 + -1x2 = 0
40 + -1x2 = -9 + 0
40 + -1x2 = -9

Add '-40' to each side of the equation.
40 + -40 + -1x2 = -9 + -40

Combine like terms: 40 + -40 = 0
0 + -1x2 = -9 + -40
-1x2 = -9 + -40

Combine like terms: -9 + -40 = -49
-1x2 = -49

Divide each side by '-1'.
x2 = 49

Simplifying
x2 = 49

Take the square root of each side:
x = {-7, 7}