(X+3)2=21

Solution for (X+3)2=21 equation:

Simplifying
(X + 3) * 2 = 21

Reorder the terms:
(3 + X) * 2 = 21

Reorder the terms for easier multiplication:
2(3 + X) = 21
(3 * 2 + X * 2) = 21
(6 + 2X) = 21

Solving
6 + 2X = 21

Solving for variable 'X'.

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

Add '-6' to each side of the equation.
6 + -6 + 2X = 21 + -6

Combine like terms: 6 + -6 = 0
0 + 2X = 21 + -6
2X = 21 + -6

Combine like terms: 21 + -6 = 15
2X = 15

Divide each side by '2'.
X = 7.5

Simplifying
X = 7.5