(2x+6)*(2x+6)=-21

Solution for (2x+6)*(2x+6)=-21 equation:

Simplifying
(2x + 6)(2x + 6) = -21

Reorder the terms:
(6 + 2x)(2x + 6) = -21

Reorder the terms:
(6 + 2x)(6 + 2x) = -21

Multiply (6 + 2x) * (6 + 2x)
(6(6 + 2x) + 2x * (6 + 2x)) = -21
((6 * 6 + 2x * 6) + 2x * (6 + 2x)) = -21
((36 + 12x) + 2x * (6 + 2x)) = -21
(36 + 12x + (6 * 2x + 2x * 2x)) = -21
(36 + 12x + (12x + 4x2)) = -21

Combine like terms: 12x + 12x = 24x
(36 + 24x + 4x2) = -21

Solving
36 + 24x + 4x2 = -21

Solving for variable 'x'.

Reorder the terms:
36 + 21 + 24x + 4x2 = -21 + 21

Combine like terms: 36 + 21 = 57
57 + 24x + 4x2 = -21 + 21

Combine like terms: -21 + 21 = 0
57 + 24x + 4x2 = 0

Begin completing the square.  Divide all terms by
4 the coefficient of the squared term: 

Divide each side by '4'.
14.25 + 6x + x2 = 0

Move the constant term to the right:

Add '-14.25' to each side of the equation.
14.25 + 6x + -14.25 + x2 = 0 + -14.25

Reorder the terms:
14.25 + -14.25 + 6x + x2 = 0 + -14.25

Combine like terms: 14.25 + -14.25 = 0.00
0.00 + 6x + x2 = 0 + -14.25
6x + x2 = 0 + -14.25

Combine like terms: 0 + -14.25 = -14.25
6x + x2 = -14.25

The x term is 6x.  Take half its coefficient (3).
Square it (9) and add it to both sides.

Add '9' to each side of the equation.
6x + 9 + x2 = -14.25 + 9

Reorder the terms:
9 + 6x + x2 = -14.25 + 9

Combine like terms: -14.25 + 9 = -5.25
9 + 6x + x2 = -5.25

Factor a perfect square on the left side:
(x + 3)(x + 3) = -5.25

Can't calculate square root of the right side.

The solution to this equation could not be determined.