2x^2-9x-20=0

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Solution for 2x^2-9x-20=0 equation:


Simplifying
2x2 + -9x + -20 = 0

Reorder the terms:
-20 + -9x + 2x2 = 0

Solving
-20 + -9x + 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'.
-10 + -4.5x + x2 = 0

Move the constant term to the right:

Add '10' to each side of the equation.
-10 + -4.5x + 10 + x2 = 0 + 10

Reorder the terms:
-10 + 10 + -4.5x + x2 = 0 + 10

Combine like terms: -10 + 10 = 0
0 + -4.5x + x2 = 0 + 10
-4.5x + x2 = 0 + 10

Combine like terms: 0 + 10 = 10
-4.5x + x2 = 10

The x term is -4.5x.  Take half its coefficient (-2.25).
Square it (5.0625) and add it to both sides.

Add '5.0625' to each side of the equation.
-4.5x + 5.0625 + x2 = 10 + 5.0625

Reorder the terms:
5.0625 + -4.5x + x2 = 10 + 5.0625

Combine like terms: 10 + 5.0625 = 15.0625
5.0625 + -4.5x + x2 = 15.0625

Factor a perfect square on the left side:
(x + -2.25)(x + -2.25) = 15.0625

Calculate the square root of the right side: 3.881043674

Break this problem into two subproblems by setting 
(x + -2.25) equal to 3.881043674 and -3.881043674.

Subproblem 1

x + -2.25 = 3.881043674 Simplifying x + -2.25 = 3.881043674 Reorder the terms: -2.25 + x = 3.881043674 Solving -2.25 + x = 3.881043674 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.25' to each side of the equation. -2.25 + 2.25 + x = 3.881043674 + 2.25 Combine like terms: -2.25 + 2.25 = 0.00 0.00 + x = 3.881043674 + 2.25 x = 3.881043674 + 2.25 Combine like terms: 3.881043674 + 2.25 = 6.131043674 x = 6.131043674 Simplifying x = 6.131043674

Subproblem 2

x + -2.25 = -3.881043674 Simplifying x + -2.25 = -3.881043674 Reorder the terms: -2.25 + x = -3.881043674 Solving -2.25 + x = -3.881043674 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '2.25' to each side of the equation. -2.25 + 2.25 + x = -3.881043674 + 2.25 Combine like terms: -2.25 + 2.25 = 0.00 0.00 + x = -3.881043674 + 2.25 x = -3.881043674 + 2.25 Combine like terms: -3.881043674 + 2.25 = -1.631043674 x = -1.631043674 Simplifying x = -1.631043674

Solution

The solution to the problem is based on the solutions from the subproblems. x = {6.131043674, -1.631043674}

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