x^2-72x-400=0

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Solution for x^2-72x-400=0 equation:


Simplifying
x2 + -72x + -400 = 0

Reorder the terms:
-400 + -72x + x2 = 0

Solving
-400 + -72x + x2 = 0

Solving for variable 'x'.

Begin completing the square.

Move the constant term to the right:

Add '400' to each side of the equation.
-400 + -72x + 400 + x2 = 0 + 400

Reorder the terms:
-400 + 400 + -72x + x2 = 0 + 400

Combine like terms: -400 + 400 = 0
0 + -72x + x2 = 0 + 400
-72x + x2 = 0 + 400

Combine like terms: 0 + 400 = 400
-72x + x2 = 400

The x term is -72x.  Take half its coefficient (-36).
Square it (1296) and add it to both sides.

Add '1296' to each side of the equation.
-72x + 1296 + x2 = 400 + 1296

Reorder the terms:
1296 + -72x + x2 = 400 + 1296

Combine like terms: 400 + 1296 = 1696
1296 + -72x + x2 = 1696

Factor a perfect square on the left side:
(x + -36)(x + -36) = 1696

Calculate the square root of the right side: 41.182520564

Break this problem into two subproblems by setting 
(x + -36) equal to 41.182520564 and -41.182520564.

Subproblem 1

x + -36 = 41.182520564 Simplifying x + -36 = 41.182520564 Reorder the terms: -36 + x = 41.182520564 Solving -36 + x = 41.182520564 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '36' to each side of the equation. -36 + 36 + x = 41.182520564 + 36 Combine like terms: -36 + 36 = 0 0 + x = 41.182520564 + 36 x = 41.182520564 + 36 Combine like terms: 41.182520564 + 36 = 77.182520564 x = 77.182520564 Simplifying x = 77.182520564

Subproblem 2

x + -36 = -41.182520564 Simplifying x + -36 = -41.182520564 Reorder the terms: -36 + x = -41.182520564 Solving -36 + x = -41.182520564 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '36' to each side of the equation. -36 + 36 + x = -41.182520564 + 36 Combine like terms: -36 + 36 = 0 0 + x = -41.182520564 + 36 x = -41.182520564 + 36 Combine like terms: -41.182520564 + 36 = -5.182520564 x = -5.182520564 Simplifying x = -5.182520564

Solution

The solution to the problem is based on the solutions from the subproblems. x = {77.182520564, -5.182520564}

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