7x^2+x-20=0

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


Simplifying
7x2 + x + -20 = 0

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

Solving
-20 + x + 7x2 = 0

Solving for variable 'x'.

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

Divide each side by '7'.
-2.857142857 + 0.1428571429x + x2 = 0

Move the constant term to the right:

Add '2.857142857' to each side of the equation.
-2.857142857 + 0.1428571429x + 2.857142857 + x2 = 0 + 2.857142857

Reorder the terms:
-2.857142857 + 2.857142857 + 0.1428571429x + x2 = 0 + 2.857142857

Combine like terms: -2.857142857 + 2.857142857 = 0.000000000
0.000000000 + 0.1428571429x + x2 = 0 + 2.857142857
0.1428571429x + x2 = 0 + 2.857142857

Combine like terms: 0 + 2.857142857 = 2.857142857
0.1428571429x + x2 = 2.857142857

The x term is x.  Take half its coefficient (0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
0.1428571429x + 0.25 + x2 = 2.857142857 + 0.25

Reorder the terms:
0.25 + 0.1428571429x + x2 = 2.857142857 + 0.25

Combine like terms: 2.857142857 + 0.25 = 3.107142857
0.25 + 0.1428571429x + x2 = 3.107142857

Factor a perfect square on the left side:
(x + 0.5)(x + 0.5) = 3.107142857

Calculate the square root of the right side: 1.762708954

Break this problem into two subproblems by setting 
(x + 0.5) equal to 1.762708954 and -1.762708954.

Subproblem 1

x + 0.5 = 1.762708954 Simplifying x + 0.5 = 1.762708954 Reorder the terms: 0.5 + x = 1.762708954 Solving 0.5 + x = 1.762708954 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5' to each side of the equation. 0.5 + -0.5 + x = 1.762708954 + -0.5 Combine like terms: 0.5 + -0.5 = 0.0 0.0 + x = 1.762708954 + -0.5 x = 1.762708954 + -0.5 Combine like terms: 1.762708954 + -0.5 = 1.262708954 x = 1.262708954 Simplifying x = 1.262708954

Subproblem 2

x + 0.5 = -1.762708954 Simplifying x + 0.5 = -1.762708954 Reorder the terms: 0.5 + x = -1.762708954 Solving 0.5 + x = -1.762708954 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.5' to each side of the equation. 0.5 + -0.5 + x = -1.762708954 + -0.5 Combine like terms: 0.5 + -0.5 = 0.0 0.0 + x = -1.762708954 + -0.5 x = -1.762708954 + -0.5 Combine like terms: -1.762708954 + -0.5 = -2.262708954 x = -2.262708954 Simplifying x = -2.262708954

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.262708954, -2.262708954}

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