x^2+2x=72

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Solution for x^2+2x=72 equation:


Simplifying
x2 + 2x = 72

Reorder the terms:
2x + x2 = 72

Solving
2x + x2 = 72

Solving for variable 'x'.

Reorder the terms:
-72 + 2x + x2 = 72 + -72

Combine like terms: 72 + -72 = 0
-72 + 2x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '72' to each side of the equation.
-72 + 2x + 72 + x2 = 0 + 72

Reorder the terms:
-72 + 72 + 2x + x2 = 0 + 72

Combine like terms: -72 + 72 = 0
0 + 2x + x2 = 0 + 72
2x + x2 = 0 + 72

Combine like terms: 0 + 72 = 72
2x + x2 = 72

The x term is 2x.  Take half its coefficient (1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
2x + 1 + x2 = 72 + 1

Reorder the terms:
1 + 2x + x2 = 72 + 1

Combine like terms: 72 + 1 = 73
1 + 2x + x2 = 73

Factor a perfect square on the left side:
(x + 1)(x + 1) = 73

Calculate the square root of the right side: 8.544003745

Break this problem into two subproblems by setting 
(x + 1) equal to 8.544003745 and -8.544003745.

Subproblem 1

x + 1 = 8.544003745 Simplifying x + 1 = 8.544003745 Reorder the terms: 1 + x = 8.544003745 Solving 1 + x = 8.544003745 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1' to each side of the equation. 1 + -1 + x = 8.544003745 + -1 Combine like terms: 1 + -1 = 0 0 + x = 8.544003745 + -1 x = 8.544003745 + -1 Combine like terms: 8.544003745 + -1 = 7.544003745 x = 7.544003745 Simplifying x = 7.544003745

Subproblem 2

x + 1 = -8.544003745 Simplifying x + 1 = -8.544003745 Reorder the terms: 1 + x = -8.544003745 Solving 1 + x = -8.544003745 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1' to each side of the equation. 1 + -1 + x = -8.544003745 + -1 Combine like terms: 1 + -1 = 0 0 + x = -8.544003745 + -1 x = -8.544003745 + -1 Combine like terms: -8.544003745 + -1 = -9.544003745 x = -9.544003745 Simplifying x = -9.544003745

Solution

The solution to the problem is based on the solutions from the subproblems. x = {7.544003745, -9.544003745}

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