87x^2-42=121x

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Solution for 87x^2-42=121x equation:


Simplifying
87x2 + -42 = 121x

Reorder the terms:
-42 + 87x2 = 121x

Solving
-42 + 87x2 = 121x

Solving for variable 'x'.

Reorder the terms:
-42 + -121x + 87x2 = 121x + -121x

Combine like terms: 121x + -121x = 0
-42 + -121x + 87x2 = 0

Begin completing the square.  Divide all terms by
87 the coefficient of the squared term: 

Divide each side by '87'.
-0.4827586207 + -1.390804598x + x2 = 0

Move the constant term to the right:

Add '0.4827586207' to each side of the equation.
-0.4827586207 + -1.390804598x + 0.4827586207 + x2 = 0 + 0.4827586207

Reorder the terms:
-0.4827586207 + 0.4827586207 + -1.390804598x + x2 = 0 + 0.4827586207

Combine like terms: -0.4827586207 + 0.4827586207 = 0.0000000000
0.0000000000 + -1.390804598x + x2 = 0 + 0.4827586207
-1.390804598x + x2 = 0 + 0.4827586207

Combine like terms: 0 + 0.4827586207 = 0.4827586207
-1.390804598x + x2 = 0.4827586207

The x term is -1.390804598x.  Take half its coefficient (-0.695402299).
Square it (0.4835843575) and add it to both sides.

Add '0.4835843575' to each side of the equation.
-1.390804598x + 0.4835843575 + x2 = 0.4827586207 + 0.4835843575

Reorder the terms:
0.4835843575 + -1.390804598x + x2 = 0.4827586207 + 0.4835843575

Combine like terms: 0.4827586207 + 0.4835843575 = 0.9663429782
0.4835843575 + -1.390804598x + x2 = 0.9663429782

Factor a perfect square on the left side:
(x + -0.695402299)(x + -0.695402299) = 0.9663429782

Calculate the square root of the right side: 0.983027455

Break this problem into two subproblems by setting 
(x + -0.695402299) equal to 0.983027455 and -0.983027455.

Subproblem 1

x + -0.695402299 = 0.983027455 Simplifying x + -0.695402299 = 0.983027455 Reorder the terms: -0.695402299 + x = 0.983027455 Solving -0.695402299 + x = 0.983027455 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.695402299' to each side of the equation. -0.695402299 + 0.695402299 + x = 0.983027455 + 0.695402299 Combine like terms: -0.695402299 + 0.695402299 = 0.000000000 0.000000000 + x = 0.983027455 + 0.695402299 x = 0.983027455 + 0.695402299 Combine like terms: 0.983027455 + 0.695402299 = 1.678429754 x = 1.678429754 Simplifying x = 1.678429754

Subproblem 2

x + -0.695402299 = -0.983027455 Simplifying x + -0.695402299 = -0.983027455 Reorder the terms: -0.695402299 + x = -0.983027455 Solving -0.695402299 + x = -0.983027455 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.695402299' to each side of the equation. -0.695402299 + 0.695402299 + x = -0.983027455 + 0.695402299 Combine like terms: -0.695402299 + 0.695402299 = 0.000000000 0.000000000 + x = -0.983027455 + 0.695402299 x = -0.983027455 + 0.695402299 Combine like terms: -0.983027455 + 0.695402299 = -0.287625156 x = -0.287625156 Simplifying x = -0.287625156

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.678429754, -0.287625156}

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