2x^2+7x-4=20

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Solution for 2x^2+7x-4=20 equation:


Simplifying
2x2 + 7x + -4 = 20

Reorder the terms:
-4 + 7x + 2x2 = 20

Solving
-4 + 7x + 2x2 = 20

Solving for variable 'x'.

Reorder the terms:
-4 + -20 + 7x + 2x2 = 20 + -20

Combine like terms: -4 + -20 = -24
-24 + 7x + 2x2 = 20 + -20

Combine like terms: 20 + -20 = 0
-24 + 7x + 2x2 = 0

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

Divide each side by '2'.
-12 + 3.5x + x2 = 0

Move the constant term to the right:

Add '12' to each side of the equation.
-12 + 3.5x + 12 + x2 = 0 + 12

Reorder the terms:
-12 + 12 + 3.5x + x2 = 0 + 12

Combine like terms: -12 + 12 = 0
0 + 3.5x + x2 = 0 + 12
3.5x + x2 = 0 + 12

Combine like terms: 0 + 12 = 12
3.5x + x2 = 12

The x term is 3.5x.  Take half its coefficient (1.75).
Square it (3.0625) and add it to both sides.

Add '3.0625' to each side of the equation.
3.5x + 3.0625 + x2 = 12 + 3.0625

Reorder the terms:
3.0625 + 3.5x + x2 = 12 + 3.0625

Combine like terms: 12 + 3.0625 = 15.0625
3.0625 + 3.5x + x2 = 15.0625

Factor a perfect square on the left side:
(x + 1.75)(x + 1.75) = 15.0625

Calculate the square root of the right side: 3.881043674

Break this problem into two subproblems by setting 
(x + 1.75) equal to 3.881043674 and -3.881043674.

Subproblem 1

x + 1.75 = 3.881043674 Simplifying x + 1.75 = 3.881043674 Reorder the terms: 1.75 + x = 3.881043674 Solving 1.75 + x = 3.881043674 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.75' to each side of the equation. 1.75 + -1.75 + x = 3.881043674 + -1.75 Combine like terms: 1.75 + -1.75 = 0.00 0.00 + x = 3.881043674 + -1.75 x = 3.881043674 + -1.75 Combine like terms: 3.881043674 + -1.75 = 2.131043674 x = 2.131043674 Simplifying x = 2.131043674

Subproblem 2

x + 1.75 = -3.881043674 Simplifying x + 1.75 = -3.881043674 Reorder the terms: 1.75 + x = -3.881043674 Solving 1.75 + x = -3.881043674 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.75' to each side of the equation. 1.75 + -1.75 + x = -3.881043674 + -1.75 Combine like terms: 1.75 + -1.75 = 0.00 0.00 + x = -3.881043674 + -1.75 x = -3.881043674 + -1.75 Combine like terms: -3.881043674 + -1.75 = -5.631043674 x = -5.631043674 Simplifying x = -5.631043674

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.131043674, -5.631043674}

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