21x^2+12x-1=

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Solution for 21x^2+12x-1= equation:


Simplifying
21x2 + 12x + -1 = 0

Reorder the terms:
-1 + 12x + 21x2 = 0

Solving
-1 + 12x + 21x2 = 0

Solving for variable 'x'.

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

Divide each side by '21'.
-0.04761904762 + 0.5714285714x + x2 = 0

Move the constant term to the right:

Add '0.04761904762' to each side of the equation.
-0.04761904762 + 0.5714285714x + 0.04761904762 + x2 = 0 + 0.04761904762

Reorder the terms:
-0.04761904762 + 0.04761904762 + 0.5714285714x + x2 = 0 + 0.04761904762

Combine like terms: -0.04761904762 + 0.04761904762 = 0.00000000000
0.00000000000 + 0.5714285714x + x2 = 0 + 0.04761904762
0.5714285714x + x2 = 0 + 0.04761904762

Combine like terms: 0 + 0.04761904762 = 0.04761904762
0.5714285714x + x2 = 0.04761904762

The x term is 0.5714285714x.  Take half its coefficient (0.2857142857).
Square it (0.08163265305) and add it to both sides.

Add '0.08163265305' to each side of the equation.
0.5714285714x + 0.08163265305 + x2 = 0.04761904762 + 0.08163265305

Reorder the terms:
0.08163265305 + 0.5714285714x + x2 = 0.04761904762 + 0.08163265305

Combine like terms: 0.04761904762 + 0.08163265305 = 0.12925170067
0.08163265305 + 0.5714285714x + x2 = 0.12925170067

Factor a perfect square on the left side:
(x + 0.2857142857)(x + 0.2857142857) = 0.12925170067

Calculate the square root of the right side: 0.359515925

Break this problem into two subproblems by setting 
(x + 0.2857142857) equal to 0.359515925 and -0.359515925.

Subproblem 1

x + 0.2857142857 = 0.359515925 Simplifying x + 0.2857142857 = 0.359515925 Reorder the terms: 0.2857142857 + x = 0.359515925 Solving 0.2857142857 + x = 0.359515925 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2857142857' to each side of the equation. 0.2857142857 + -0.2857142857 + x = 0.359515925 + -0.2857142857 Combine like terms: 0.2857142857 + -0.2857142857 = 0.0000000000 0.0000000000 + x = 0.359515925 + -0.2857142857 x = 0.359515925 + -0.2857142857 Combine like terms: 0.359515925 + -0.2857142857 = 0.0738016393 x = 0.0738016393 Simplifying x = 0.0738016393

Subproblem 2

x + 0.2857142857 = -0.359515925 Simplifying x + 0.2857142857 = -0.359515925 Reorder the terms: 0.2857142857 + x = -0.359515925 Solving 0.2857142857 + x = -0.359515925 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2857142857' to each side of the equation. 0.2857142857 + -0.2857142857 + x = -0.359515925 + -0.2857142857 Combine like terms: 0.2857142857 + -0.2857142857 = 0.0000000000 0.0000000000 + x = -0.359515925 + -0.2857142857 x = -0.359515925 + -0.2857142857 Combine like terms: -0.359515925 + -0.2857142857 = -0.6452302107 x = -0.6452302107 Simplifying x = -0.6452302107

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.0738016393, -0.6452302107}

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