2x^2+42x-57=0

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Solution for 2x^2+42x-57=0 equation:


Simplifying
2x2 + 42x + -57 = 0

Reorder the terms:
-57 + 42x + 2x2 = 0

Solving
-57 + 42x + 2x2 = 0

Solving for variable 'x'.

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

Divide each side by '2'.
-28.5 + 21x + x2 = 0

Move the constant term to the right:

Add '28.5' to each side of the equation.
-28.5 + 21x + 28.5 + x2 = 0 + 28.5

Reorder the terms:
-28.5 + 28.5 + 21x + x2 = 0 + 28.5

Combine like terms: -28.5 + 28.5 = 0.0
0.0 + 21x + x2 = 0 + 28.5
21x + x2 = 0 + 28.5

Combine like terms: 0 + 28.5 = 28.5
21x + x2 = 28.5

The x term is 21x.  Take half its coefficient (10.5).
Square it (110.25) and add it to both sides.

Add '110.25' to each side of the equation.
21x + 110.25 + x2 = 28.5 + 110.25

Reorder the terms:
110.25 + 21x + x2 = 28.5 + 110.25

Combine like terms: 28.5 + 110.25 = 138.75
110.25 + 21x + x2 = 138.75

Factor a perfect square on the left side:
(x + 10.5)(x + 10.5) = 138.75

Calculate the square root of the right side: 11.779218989

Break this problem into two subproblems by setting 
(x + 10.5) equal to 11.779218989 and -11.779218989.

Subproblem 1

x + 10.5 = 11.779218989 Simplifying x + 10.5 = 11.779218989 Reorder the terms: 10.5 + x = 11.779218989 Solving 10.5 + x = 11.779218989 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10.5' to each side of the equation. 10.5 + -10.5 + x = 11.779218989 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = 11.779218989 + -10.5 x = 11.779218989 + -10.5 Combine like terms: 11.779218989 + -10.5 = 1.279218989 x = 1.279218989 Simplifying x = 1.279218989

Subproblem 2

x + 10.5 = -11.779218989 Simplifying x + 10.5 = -11.779218989 Reorder the terms: 10.5 + x = -11.779218989 Solving 10.5 + x = -11.779218989 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-10.5' to each side of the equation. 10.5 + -10.5 + x = -11.779218989 + -10.5 Combine like terms: 10.5 + -10.5 = 0.0 0.0 + x = -11.779218989 + -10.5 x = -11.779218989 + -10.5 Combine like terms: -11.779218989 + -10.5 = -22.279218989 x = -22.279218989 Simplifying x = -22.279218989

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.279218989, -22.279218989}

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