x(x+7)=20

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Solution for x(x+7)=20 equation:


Simplifying
x(x + 7) = 20

Reorder the terms:
x(7 + x) = 20
(7 * x + x * x) = 20
(7x + x2) = 20

Solving
7x + x2 = 20

Solving for variable 'x'.

Reorder the terms:
-20 + 7x + x2 = 20 + -20

Combine like terms: 20 + -20 = 0
-20 + 7x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '20' to each side of the equation.
-20 + 7x + 20 + x2 = 0 + 20

Reorder the terms:
-20 + 20 + 7x + x2 = 0 + 20

Combine like terms: -20 + 20 = 0
0 + 7x + x2 = 0 + 20
7x + x2 = 0 + 20

Combine like terms: 0 + 20 = 20
7x + x2 = 20

The x term is 7x.  Take half its coefficient (3.5).
Square it (12.25) and add it to both sides.

Add '12.25' to each side of the equation.
7x + 12.25 + x2 = 20 + 12.25

Reorder the terms:
12.25 + 7x + x2 = 20 + 12.25

Combine like terms: 20 + 12.25 = 32.25
12.25 + 7x + x2 = 32.25

Factor a perfect square on the left side:
(x + 3.5)(x + 3.5) = 32.25

Calculate the square root of the right side: 5.678908346

Break this problem into two subproblems by setting 
(x + 3.5) equal to 5.678908346 and -5.678908346.

Subproblem 1

x + 3.5 = 5.678908346 Simplifying x + 3.5 = 5.678908346 Reorder the terms: 3.5 + x = 5.678908346 Solving 3.5 + x = 5.678908346 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.5' to each side of the equation. 3.5 + -3.5 + x = 5.678908346 + -3.5 Combine like terms: 3.5 + -3.5 = 0.0 0.0 + x = 5.678908346 + -3.5 x = 5.678908346 + -3.5 Combine like terms: 5.678908346 + -3.5 = 2.178908346 x = 2.178908346 Simplifying x = 2.178908346

Subproblem 2

x + 3.5 = -5.678908346 Simplifying x + 3.5 = -5.678908346 Reorder the terms: 3.5 + x = -5.678908346 Solving 3.5 + x = -5.678908346 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-3.5' to each side of the equation. 3.5 + -3.5 + x = -5.678908346 + -3.5 Combine like terms: 3.5 + -3.5 = 0.0 0.0 + x = -5.678908346 + -3.5 x = -5.678908346 + -3.5 Combine like terms: -5.678908346 + -3.5 = -9.178908346 x = -9.178908346 Simplifying x = -9.178908346

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.178908346, -9.178908346}

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