x^2+21x+3=

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Solution for x^2+21x+3= equation:


Simplifying
x2 + 21x + 3 = 0

Reorder the terms:
3 + 21x + x2 = 0

Solving
3 + 21x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '-3' to each side of the equation.
3 + 21x + -3 + x2 = 0 + -3

Reorder the terms:
3 + -3 + 21x + x2 = 0 + -3

Combine like terms: 3 + -3 = 0
0 + 21x + x2 = 0 + -3
21x + x2 = 0 + -3

Combine like terms: 0 + -3 = -3
21x + x2 = -3

The x term is 21x.  Take half its coefficient (10.5).
Square it (110.25) and add it to both sides.

Add '110.25' to each side of the equation.
21x + 110.25 + x2 = -3 + 110.25

Reorder the terms:
110.25 + 21x + x2 = -3 + 110.25

Combine like terms: -3 + 110.25 = 107.25
110.25 + 21x + x2 = 107.25

Factor a perfect square on the left side:
(x + 10.5)(x + 10.5) = 107.25

Calculate the square root of the right side: 10.356157589

Break this problem into two subproblems by setting 
(x + 10.5) equal to 10.356157589 and -10.356157589.

Subproblem 1

x + 10.5 = 10.356157589 Simplifying x + 10.5 = 10.356157589 Reorder the terms: 10.5 + x = 10.356157589 Solving 10.5 + x = 10.356157589 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10.5' to each side of the equation. 10.5 + -10.5 + x = 10.356157589 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = 10.356157589 + -10.5 x = 10.356157589 + -10.5 Combine like terms: 10.356157589 + -10.5 = -0.143842411 x = -0.143842411 Simplifying x = -0.143842411

Subproblem 2

x + 10.5 = -10.356157589 Simplifying x + 10.5 = -10.356157589 Reorder the terms: 10.5 + x = -10.356157589 Solving 10.5 + x = -10.356157589 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10.5' to each side of the equation. 10.5 + -10.5 + x = -10.356157589 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = -10.356157589 + -10.5 x = -10.356157589 + -10.5 Combine like terms: -10.356157589 + -10.5 = -20.856157589 x = -20.856157589 Simplifying x = -20.856157589

Solution

The solution to the problem is based on the solutions from the subproblems. x = {-0.143842411, -20.856157589}

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