(k+3)(k-3)=20

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

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

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

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

Multiply (3 + k) * (-3 + k)
(3(-3 + k) + k(-3 + k)) = 20
((-3 * 3 + k * 3) + k(-3 + k)) = 20
((-9 + 3k) + k(-3 + k)) = 20
(-9 + 3k + (-3 * k + k * k)) = 20
(-9 + 3k + (-3k + k2)) = 20

Combine like terms: 3k + -3k = 0
(-9 + 0 + k2) = 20
(-9 + k2) = 20

Solving
-9 + k2 = 20

Solving for variable 'k'.

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

Add '9' to each side of the equation.
-9 + 9 + k2 = 20 + 9

Combine like terms: -9 + 9 = 0
0 + k2 = 20 + 9
k2 = 20 + 9

Combine like terms: 20 + 9 = 29
k2 = 29

Simplifying
k2 = 29

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