81x^2+x-4=0

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Solution for 81x^2+x-4=0 equation:


Simplifying
81x2 + x + -4 = 0

Reorder the terms:
-4 + x + 81x2 = 0

Solving
-4 + x + 81x2 = 0

Solving for variable 'x'.

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

Divide each side by '81'.
-0.04938271605 + 0.01234567901x + x2 = 0

Move the constant term to the right:

Add '0.04938271605' to each side of the equation.
-0.04938271605 + 0.01234567901x + 0.04938271605 + x2 = 0 + 0.04938271605

Reorder the terms:
-0.04938271605 + 0.04938271605 + 0.01234567901x + x2 = 0 + 0.04938271605

Combine like terms: -0.04938271605 + 0.04938271605 = 0.00000000000
0.00000000000 + 0.01234567901x + x2 = 0 + 0.04938271605
0.01234567901x + x2 = 0 + 0.04938271605

Combine like terms: 0 + 0.04938271605 = 0.04938271605
0.01234567901x + x2 = 0.04938271605

The x term is x.  Take half its coefficient (0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
0.01234567901x + 0.25 + x2 = 0.04938271605 + 0.25

Reorder the terms:
0.25 + 0.01234567901x + x2 = 0.04938271605 + 0.25

Combine like terms: 0.04938271605 + 0.25 = 0.29938271605
0.25 + 0.01234567901x + x2 = 0.29938271605

Factor a perfect square on the left side:
(x + 0.5)(x + 0.5) = 0.29938271605

Calculate the square root of the right side: 0.547158767

Break this problem into two subproblems by setting 
(x + 0.5) equal to 0.547158767 and -0.547158767.

Subproblem 1

x + 0.5 = 0.547158767 Simplifying x + 0.5 = 0.547158767 Reorder the terms: 0.5 + x = 0.547158767 Solving 0.5 + x = 0.547158767 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5' to each side of the equation. 0.5 + -0.5 + x = 0.547158767 + -0.5 Combine like terms: 0.5 + -0.5 = 0.0 0.0 + x = 0.547158767 + -0.5 x = 0.547158767 + -0.5 Combine like terms: 0.547158767 + -0.5 = 0.047158767 x = 0.047158767 Simplifying x = 0.047158767

Subproblem 2

x + 0.5 = -0.547158767 Simplifying x + 0.5 = -0.547158767 Reorder the terms: 0.5 + x = -0.547158767 Solving 0.5 + x = -0.547158767 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5' to each side of the equation. 0.5 + -0.5 + x = -0.547158767 + -0.5 Combine like terms: 0.5 + -0.5 = 0.0 0.0 + x = -0.547158767 + -0.5 x = -0.547158767 + -0.5 Combine like terms: -0.547158767 + -0.5 = -1.047158767 x = -1.047158767 Simplifying x = -1.047158767

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.047158767, -1.047158767}

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