x^2=81x-100

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Solution for x^2=81x-100 equation:


Simplifying
x2 = 81x + -100

Reorder the terms:
x2 = -100 + 81x

Solving
x2 = -100 + 81x

Solving for variable 'x'.

Reorder the terms:
100 + -81x + x2 = -100 + 81x + 100 + -81x

Reorder the terms:
100 + -81x + x2 = -100 + 100 + 81x + -81x

Combine like terms: -100 + 100 = 0
100 + -81x + x2 = 0 + 81x + -81x
100 + -81x + x2 = 81x + -81x

Combine like terms: 81x + -81x = 0
100 + -81x + x2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-100' to each side of the equation.
100 + -81x + -100 + x2 = 0 + -100

Reorder the terms:
100 + -100 + -81x + x2 = 0 + -100

Combine like terms: 100 + -100 = 0
0 + -81x + x2 = 0 + -100
-81x + x2 = 0 + -100

Combine like terms: 0 + -100 = -100
-81x + x2 = -100

The x term is -81x.  Take half its coefficient (-40.5).
Square it (1640.25) and add it to both sides.

Add '1640.25' to each side of the equation.
-81x + 1640.25 + x2 = -100 + 1640.25

Reorder the terms:
1640.25 + -81x + x2 = -100 + 1640.25

Combine like terms: -100 + 1640.25 = 1540.25
1640.25 + -81x + x2 = 1540.25

Factor a perfect square on the left side:
(x + -40.5)(x + -40.5) = 1540.25

Calculate the square root of the right side: 39.246018906

Break this problem into two subproblems by setting 
(x + -40.5) equal to 39.246018906 and -39.246018906.

Subproblem 1

x + -40.5 = 39.246018906 Simplifying x + -40.5 = 39.246018906 Reorder the terms: -40.5 + x = 39.246018906 Solving -40.5 + x = 39.246018906 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '40.5' to each side of the equation. -40.5 + 40.5 + x = 39.246018906 + 40.5 Combine like terms: -40.5 + 40.5 = 0.0 0.0 + x = 39.246018906 + 40.5 x = 39.246018906 + 40.5 Combine like terms: 39.246018906 + 40.5 = 79.746018906 x = 79.746018906 Simplifying x = 79.746018906

Subproblem 2

x + -40.5 = -39.246018906 Simplifying x + -40.5 = -39.246018906 Reorder the terms: -40.5 + x = -39.246018906 Solving -40.5 + x = -39.246018906 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '40.5' to each side of the equation. -40.5 + 40.5 + x = -39.246018906 + 40.5 Combine like terms: -40.5 + 40.5 = 0.0 0.0 + x = -39.246018906 + 40.5 x = -39.246018906 + 40.5 Combine like terms: -39.246018906 + 40.5 = 1.253981094 x = 1.253981094 Simplifying x = 1.253981094

Solution

The solution to the problem is based on the solutions from the subproblems. x = {79.746018906, 1.253981094}

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