12x^2-2x-21=

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


Simplifying
12x2 + -2x + -21 = 0

Reorder the terms:
-21 + -2x + 12x2 = 0

Solving
-21 + -2x + 12x2 = 0

Solving for variable 'x'.

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

Divide each side by '12'.
-1.75 + -0.1666666667x + x2 = 0

Move the constant term to the right:

Add '1.75' to each side of the equation.
-1.75 + -0.1666666667x + 1.75 + x2 = 0 + 1.75

Reorder the terms:
-1.75 + 1.75 + -0.1666666667x + x2 = 0 + 1.75

Combine like terms: -1.75 + 1.75 = 0.00
0.00 + -0.1666666667x + x2 = 0 + 1.75
-0.1666666667x + x2 = 0 + 1.75

Combine like terms: 0 + 1.75 = 1.75
-0.1666666667x + x2 = 1.75

The x term is -0.1666666667x.  Take half its coefficient (-0.08333333335).
Square it (0.006944444447) and add it to both sides.

Add '0.006944444447' to each side of the equation.
-0.1666666667x + 0.006944444447 + x2 = 1.75 + 0.006944444447

Reorder the terms:
0.006944444447 + -0.1666666667x + x2 = 1.75 + 0.006944444447

Combine like terms: 1.75 + 0.006944444447 = 1.756944444447
0.006944444447 + -0.1666666667x + x2 = 1.756944444447

Factor a perfect square on the left side:
(x + -0.08333333335)(x + -0.08333333335) = 1.756944444447

Calculate the square root of the right side: 1.32549781

Break this problem into two subproblems by setting 
(x + -0.08333333335) equal to 1.32549781 and -1.32549781.

Subproblem 1

x + -0.08333333335 = 1.32549781 Simplifying x + -0.08333333335 = 1.32549781 Reorder the terms: -0.08333333335 + x = 1.32549781 Solving -0.08333333335 + x = 1.32549781 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.08333333335' to each side of the equation. -0.08333333335 + 0.08333333335 + x = 1.32549781 + 0.08333333335 Combine like terms: -0.08333333335 + 0.08333333335 = 0.00000000000 0.00000000000 + x = 1.32549781 + 0.08333333335 x = 1.32549781 + 0.08333333335 Combine like terms: 1.32549781 + 0.08333333335 = 1.40883114335 x = 1.40883114335 Simplifying x = 1.40883114335

Subproblem 2

x + -0.08333333335 = -1.32549781 Simplifying x + -0.08333333335 = -1.32549781 Reorder the terms: -0.08333333335 + x = -1.32549781 Solving -0.08333333335 + x = -1.32549781 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.08333333335' to each side of the equation. -0.08333333335 + 0.08333333335 + x = -1.32549781 + 0.08333333335 Combine like terms: -0.08333333335 + 0.08333333335 = 0.00000000000 0.00000000000 + x = -1.32549781 + 0.08333333335 x = -1.32549781 + 0.08333333335 Combine like terms: -1.32549781 + 0.08333333335 = -1.24216447665 x = -1.24216447665 Simplifying x = -1.24216447665

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.40883114335, -1.24216447665}

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