4x^2+20x-55=0

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Solution for 4x^2+20x-55=0 equation:


Simplifying
4x2 + 20x + -55 = 0

Reorder the terms:
-55 + 20x + 4x2 = 0

Solving
-55 + 20x + 4x2 = 0

Solving for variable 'x'.

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

Divide each side by '4'.
-13.75 + 5x + x2 = 0

Move the constant term to the right:

Add '13.75' to each side of the equation.
-13.75 + 5x + 13.75 + x2 = 0 + 13.75

Reorder the terms:
-13.75 + 13.75 + 5x + x2 = 0 + 13.75

Combine like terms: -13.75 + 13.75 = 0.00
0.00 + 5x + x2 = 0 + 13.75
5x + x2 = 0 + 13.75

Combine like terms: 0 + 13.75 = 13.75
5x + x2 = 13.75

The x term is 5x.  Take half its coefficient (2.5).
Square it (6.25) and add it to both sides.

Add '6.25' to each side of the equation.
5x + 6.25 + x2 = 13.75 + 6.25

Reorder the terms:
6.25 + 5x + x2 = 13.75 + 6.25

Combine like terms: 13.75 + 6.25 = 20
6.25 + 5x + x2 = 20

Factor a perfect square on the left side:
(x + 2.5)(x + 2.5) = 20

Calculate the square root of the right side: 4.472135955

Break this problem into two subproblems by setting 
(x + 2.5) equal to 4.472135955 and -4.472135955.

Subproblem 1

x + 2.5 = 4.472135955 Simplifying x + 2.5 = 4.472135955 Reorder the terms: 2.5 + x = 4.472135955 Solving 2.5 + x = 4.472135955 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-2.5' to each side of the equation. 2.5 + -2.5 + x = 4.472135955 + -2.5 Combine like terms: 2.5 + -2.5 = 0.0 0.0 + x = 4.472135955 + -2.5 x = 4.472135955 + -2.5 Combine like terms: 4.472135955 + -2.5 = 1.972135955 x = 1.972135955 Simplifying x = 1.972135955

Subproblem 2

x + 2.5 = -4.472135955 Simplifying x + 2.5 = -4.472135955 Reorder the terms: 2.5 + x = -4.472135955 Solving 2.5 + x = -4.472135955 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-2.5' to each side of the equation. 2.5 + -2.5 + x = -4.472135955 + -2.5 Combine like terms: 2.5 + -2.5 = 0.0 0.0 + x = -4.472135955 + -2.5 x = -4.472135955 + -2.5 Combine like terms: -4.472135955 + -2.5 = -6.972135955 x = -6.972135955 Simplifying x = -6.972135955

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.972135955, -6.972135955}

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