-5x^2+7x+20=0

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Solution for -5x^2+7x+20=0 equation:


Simplifying
-5x2 + 7x + 20 = 0

Reorder the terms:
20 + 7x + -5x2 = 0

Solving
20 + 7x + -5x2 = 0

Solving for variable 'x'.

Begin completing the square.  Divide all terms by
-5 the coefficient of the squared term: 

Divide each side by '-5'.
-4 + -1.4x + x2 = 0

Move the constant term to the right:

Add '4' to each side of the equation.
-4 + -1.4x + 4 + x2 = 0 + 4

Reorder the terms:
-4 + 4 + -1.4x + x2 = 0 + 4

Combine like terms: -4 + 4 = 0
0 + -1.4x + x2 = 0 + 4
-1.4x + x2 = 0 + 4

Combine like terms: 0 + 4 = 4
-1.4x + x2 = 4

The x term is -1.4x.  Take half its coefficient (-0.7).
Square it (0.49) and add it to both sides.

Add '0.49' to each side of the equation.
-1.4x + 0.49 + x2 = 4 + 0.49

Reorder the terms:
0.49 + -1.4x + x2 = 4 + 0.49

Combine like terms: 4 + 0.49 = 4.49
0.49 + -1.4x + x2 = 4.49

Factor a perfect square on the left side:
(x + -0.7)(x + -0.7) = 4.49

Calculate the square root of the right side: 2.11896201

Break this problem into two subproblems by setting 
(x + -0.7) equal to 2.11896201 and -2.11896201.

Subproblem 1

x + -0.7 = 2.11896201 Simplifying x + -0.7 = 2.11896201 Reorder the terms: -0.7 + x = 2.11896201 Solving -0.7 + x = 2.11896201 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.7' to each side of the equation. -0.7 + 0.7 + x = 2.11896201 + 0.7 Combine like terms: -0.7 + 0.7 = 0.0 0.0 + x = 2.11896201 + 0.7 x = 2.11896201 + 0.7 Combine like terms: 2.11896201 + 0.7 = 2.81896201 x = 2.81896201 Simplifying x = 2.81896201

Subproblem 2

x + -0.7 = -2.11896201 Simplifying x + -0.7 = -2.11896201 Reorder the terms: -0.7 + x = -2.11896201 Solving -0.7 + x = -2.11896201 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.7' to each side of the equation. -0.7 + 0.7 + x = -2.11896201 + 0.7 Combine like terms: -0.7 + 0.7 = 0.0 0.0 + x = -2.11896201 + 0.7 x = -2.11896201 + 0.7 Combine like terms: -2.11896201 + 0.7 = -1.41896201 x = -1.41896201 Simplifying x = -1.41896201

Solution

The solution to the problem is based on the solutions from the subproblems. x = {2.81896201, -1.41896201}

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