81x^2+16x-4=0

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Solution for 81x^2+16x-4=0 equation:


Simplifying
81x2 + 16x + -4 = 0

Reorder the terms:
-4 + 16x + 81x2 = 0

Solving
-4 + 16x + 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 + 0.1975308642x + x2 = 0

Move the constant term to the right:

Add '0.04938271605' to each side of the equation.
-0.04938271605 + 0.1975308642x + 0.04938271605 + x2 = 0 + 0.04938271605

Reorder the terms:
-0.04938271605 + 0.04938271605 + 0.1975308642x + x2 = 0 + 0.04938271605

Combine like terms: -0.04938271605 + 0.04938271605 = 0.00000000000
0.00000000000 + 0.1975308642x + x2 = 0 + 0.04938271605
0.1975308642x + x2 = 0 + 0.04938271605

Combine like terms: 0 + 0.04938271605 = 0.04938271605
0.1975308642x + x2 = 0.04938271605

The x term is 0.1975308642x.  Take half its coefficient (0.0987654321).
Square it (0.009754610578) and add it to both sides.

Add '0.009754610578' to each side of the equation.
0.1975308642x + 0.009754610578 + x2 = 0.04938271605 + 0.009754610578

Reorder the terms:
0.009754610578 + 0.1975308642x + x2 = 0.04938271605 + 0.009754610578

Combine like terms: 0.04938271605 + 0.009754610578 = 0.059137326628
0.009754610578 + 0.1975308642x + x2 = 0.059137326628

Factor a perfect square on the left side:
(x + 0.0987654321)(x + 0.0987654321) = 0.059137326628

Calculate the square root of the right side: 0.243181674

Break this problem into two subproblems by setting 
(x + 0.0987654321) equal to 0.243181674 and -0.243181674.

Subproblem 1

x + 0.0987654321 = 0.243181674 Simplifying x + 0.0987654321 = 0.243181674 Reorder the terms: 0.0987654321 + x = 0.243181674 Solving 0.0987654321 + x = 0.243181674 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.0987654321' to each side of the equation. 0.0987654321 + -0.0987654321 + x = 0.243181674 + -0.0987654321 Combine like terms: 0.0987654321 + -0.0987654321 = 0.0000000000 0.0000000000 + x = 0.243181674 + -0.0987654321 x = 0.243181674 + -0.0987654321 Combine like terms: 0.243181674 + -0.0987654321 = 0.1444162419 x = 0.1444162419 Simplifying x = 0.1444162419

Subproblem 2

x + 0.0987654321 = -0.243181674 Simplifying x + 0.0987654321 = -0.243181674 Reorder the terms: 0.0987654321 + x = -0.243181674 Solving 0.0987654321 + x = -0.243181674 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.0987654321' to each side of the equation. 0.0987654321 + -0.0987654321 + x = -0.243181674 + -0.0987654321 Combine like terms: 0.0987654321 + -0.0987654321 = 0.0000000000 0.0000000000 + x = -0.243181674 + -0.0987654321 x = -0.243181674 + -0.0987654321 Combine like terms: -0.243181674 + -0.0987654321 = -0.3419471061 x = -0.3419471061 Simplifying x = -0.3419471061

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.1444162419, -0.3419471061}

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