(u+3)(u-3)=8

Solution for (u+3)(u-3)=8 equation:

Simplifying
(u + 3)(u + -3) = 8

Reorder the terms:
(3 + u)(u + -3) = 8

Reorder the terms:
(3 + u)(-3 + u) = 8

Multiply (3 + u) * (-3 + u)
(3(-3 + u) + u(-3 + u)) = 8
((-3 * 3 + u * 3) + u(-3 + u)) = 8
((-9 + 3u) + u(-3 + u)) = 8
(-9 + 3u + (-3 * u + u * u)) = 8
(-9 + 3u + (-3u + u2)) = 8

Combine like terms: 3u + -3u = 0
(-9 + 0 + u2) = 8
(-9 + u2) = 8

Solving
-9 + u2 = 8

Solving for variable 'u'.

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

Add '9' to each side of the equation.
-9 + 9 + u2 = 8 + 9

Combine like terms: -9 + 9 = 0
0 + u2 = 8 + 9
u2 = 8 + 9

Combine like terms: 8 + 9 = 17
u2 = 17

Simplifying
u2 = 17

Take the square root of each side:
u = {-4.123105626, 4.123105626}