21x^2-10x-2=0

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Solution for 21x^2-10x-2=0 equation:


Simplifying
21x2 + -10x + -2 = 0

Reorder the terms:
-2 + -10x + 21x2 = 0

Solving
-2 + -10x + 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'.
-0.09523809524 + -0.4761904762x + x2 = 0

Move the constant term to the right:

Add '0.09523809524' to each side of the equation.
-0.09523809524 + -0.4761904762x + 0.09523809524 + x2 = 0 + 0.09523809524

Reorder the terms:
-0.09523809524 + 0.09523809524 + -0.4761904762x + x2 = 0 + 0.09523809524

Combine like terms: -0.09523809524 + 0.09523809524 = 0.00000000000
0.00000000000 + -0.4761904762x + x2 = 0 + 0.09523809524
-0.4761904762x + x2 = 0 + 0.09523809524

Combine like terms: 0 + 0.09523809524 = 0.09523809524
-0.4761904762x + x2 = 0.09523809524

The x term is -0.4761904762x.  Take half its coefficient (-0.2380952381).
Square it (0.05668934241) and add it to both sides.

Add '0.05668934241' to each side of the equation.
-0.4761904762x + 0.05668934241 + x2 = 0.09523809524 + 0.05668934241

Reorder the terms:
0.05668934241 + -0.4761904762x + x2 = 0.09523809524 + 0.05668934241

Combine like terms: 0.09523809524 + 0.05668934241 = 0.15192743765
0.05668934241 + -0.4761904762x + x2 = 0.15192743765

Factor a perfect square on the left side:
(x + -0.2380952381)(x + -0.2380952381) = 0.15192743765

Calculate the square root of the right side: 0.389778703

Break this problem into two subproblems by setting 
(x + -0.2380952381) equal to 0.389778703 and -0.389778703.

Subproblem 1

x + -0.2380952381 = 0.389778703 Simplifying x + -0.2380952381 = 0.389778703 Reorder the terms: -0.2380952381 + x = 0.389778703 Solving -0.2380952381 + x = 0.389778703 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.2380952381' to each side of the equation. -0.2380952381 + 0.2380952381 + x = 0.389778703 + 0.2380952381 Combine like terms: -0.2380952381 + 0.2380952381 = 0.0000000000 0.0000000000 + x = 0.389778703 + 0.2380952381 x = 0.389778703 + 0.2380952381 Combine like terms: 0.389778703 + 0.2380952381 = 0.6278739411 x = 0.6278739411 Simplifying x = 0.6278739411

Subproblem 2

x + -0.2380952381 = -0.389778703 Simplifying x + -0.2380952381 = -0.389778703 Reorder the terms: -0.2380952381 + x = -0.389778703 Solving -0.2380952381 + x = -0.389778703 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.2380952381' to each side of the equation. -0.2380952381 + 0.2380952381 + x = -0.389778703 + 0.2380952381 Combine like terms: -0.2380952381 + 0.2380952381 = 0.0000000000 0.0000000000 + x = -0.389778703 + 0.2380952381 x = -0.389778703 + 0.2380952381 Combine like terms: -0.389778703 + 0.2380952381 = -0.1516834649 x = -0.1516834649 Simplifying x = -0.1516834649

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.6278739411, -0.1516834649}

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