21=(x+2)(x+2)

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Solution for 21=(x+2)(x+2) equation:


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

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

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

Multiply (2 + x) * (2 + x)
21 = (2(2 + x) + x(2 + x))
21 = ((2 * 2 + x * 2) + x(2 + x))
21 = ((4 + 2x) + x(2 + x))
21 = (4 + 2x + (2 * x + x * x))
21 = (4 + 2x + (2x + x2))

Combine like terms: 2x + 2x = 4x
21 = (4 + 4x + x2)

Solving
21 = 4 + 4x + x2

Solving for variable 'x'.

Combine like terms: 21 + -4 = 17
17 + -4x + -1x2 = 4 + 4x + x2 + -4 + -4x + -1x2

Reorder the terms:
17 + -4x + -1x2 = 4 + -4 + 4x + -4x + x2 + -1x2

Combine like terms: 4 + -4 = 0
17 + -4x + -1x2 = 0 + 4x + -4x + x2 + -1x2
17 + -4x + -1x2 = 4x + -4x + x2 + -1x2

Combine like terms: 4x + -4x = 0
17 + -4x + -1x2 = 0 + x2 + -1x2
17 + -4x + -1x2 = x2 + -1x2

Combine like terms: x2 + -1x2 = 0
17 + -4x + -1x2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
-17 + 4x + x2 = 0

Move the constant term to the right:

Add '17' to each side of the equation.
-17 + 4x + 17 + x2 = 0 + 17

Reorder the terms:
-17 + 17 + 4x + x2 = 0 + 17

Combine like terms: -17 + 17 = 0
0 + 4x + x2 = 0 + 17
4x + x2 = 0 + 17

Combine like terms: 0 + 17 = 17
4x + x2 = 17

The x term is 4x.  Take half its coefficient (2).
Square it (4) and add it to both sides.

Add '4' to each side of the equation.
4x + 4 + x2 = 17 + 4

Reorder the terms:
4 + 4x + x2 = 17 + 4

Combine like terms: 17 + 4 = 21
4 + 4x + x2 = 21

Factor a perfect square on the left side:
(x + 2)(x + 2) = 21

Calculate the square root of the right side: 4.582575695

Break this problem into two subproblems by setting 
(x + 2) equal to 4.582575695 and -4.582575695.

Subproblem 1

x + 2 = 4.582575695 Simplifying x + 2 = 4.582575695 Reorder the terms: 2 + x = 4.582575695 Solving 2 + x = 4.582575695 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-2' to each side of the equation. 2 + -2 + x = 4.582575695 + -2 Combine like terms: 2 + -2 = 0 0 + x = 4.582575695 + -2 x = 4.582575695 + -2 Combine like terms: 4.582575695 + -2 = 2.582575695 x = 2.582575695 Simplifying x = 2.582575695

Subproblem 2

x + 2 = -4.582575695 Simplifying x + 2 = -4.582575695 Reorder the terms: 2 + x = -4.582575695 Solving 2 + x = -4.582575695 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-2' to each side of the equation. 2 + -2 + x = -4.582575695 + -2 Combine like terms: 2 + -2 = 0 0 + x = -4.582575695 + -2 x = -4.582575695 + -2 Combine like terms: -4.582575695 + -2 = -6.582575695 x = -6.582575695 Simplifying x = -6.582575695

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.582575695, -6.582575695}

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