x^2+20x=99

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Solution for x^2+20x=99 equation:


Simplifying
x2 + 20x = 99

Reorder the terms:
20x + x2 = 99

Solving
20x + x2 = 99

Solving for variable 'x'.

Reorder the terms:
-99 + 20x + x2 = 99 + -99

Combine like terms: 99 + -99 = 0
-99 + 20x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '99' to each side of the equation.
-99 + 20x + 99 + x2 = 0 + 99

Reorder the terms:
-99 + 99 + 20x + x2 = 0 + 99

Combine like terms: -99 + 99 = 0
0 + 20x + x2 = 0 + 99
20x + x2 = 0 + 99

Combine like terms: 0 + 99 = 99
20x + x2 = 99

The x term is 20x.  Take half its coefficient (10).
Square it (100) and add it to both sides.

Add '100' to each side of the equation.
20x + 100 + x2 = 99 + 100

Reorder the terms:
100 + 20x + x2 = 99 + 100

Combine like terms: 99 + 100 = 199
100 + 20x + x2 = 199

Factor a perfect square on the left side:
(x + 10)(x + 10) = 199

Calculate the square root of the right side: 14.10673598

Break this problem into two subproblems by setting 
(x + 10) equal to 14.10673598 and -14.10673598.

Subproblem 1

x + 10 = 14.10673598 Simplifying x + 10 = 14.10673598 Reorder the terms: 10 + x = 14.10673598 Solving 10 + x = 14.10673598 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10' to each side of the equation. 10 + -10 + x = 14.10673598 + -10 Combine like terms: 10 + -10 = 0 0 + x = 14.10673598 + -10 x = 14.10673598 + -10 Combine like terms: 14.10673598 + -10 = 4.10673598 x = 4.10673598 Simplifying x = 4.10673598

Subproblem 2

x + 10 = -14.10673598 Simplifying x + 10 = -14.10673598 Reorder the terms: 10 + x = -14.10673598 Solving 10 + x = -14.10673598 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10' to each side of the equation. 10 + -10 + x = -14.10673598 + -10 Combine like terms: 10 + -10 = 0 0 + x = -14.10673598 + -10 x = -14.10673598 + -10 Combine like terms: -14.10673598 + -10 = -24.10673598 x = -24.10673598 Simplifying x = -24.10673598

Solution

The solution to the problem is based on the solutions from the subproblems. x = {4.10673598, -24.10673598}

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