42x-69x+20=7x^2-8

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Solution for 42x-69x+20=7x^2-8 equation:


Simplifying
42x + -69x + 20 = 7x2 + -8

Reorder the terms:
20 + 42x + -69x = 7x2 + -8

Combine like terms: 42x + -69x = -27x
20 + -27x = 7x2 + -8

Reorder the terms:
20 + -27x = -8 + 7x2

Solving
20 + -27x = -8 + 7x2

Solving for variable 'x'.

Reorder the terms:
20 + 8 + -27x + -7x2 = -8 + 7x2 + 8 + -7x2

Combine like terms: 20 + 8 = 28
28 + -27x + -7x2 = -8 + 7x2 + 8 + -7x2

Reorder the terms:
28 + -27x + -7x2 = -8 + 8 + 7x2 + -7x2

Combine like terms: -8 + 8 = 0
28 + -27x + -7x2 = 0 + 7x2 + -7x2
28 + -27x + -7x2 = 7x2 + -7x2

Combine like terms: 7x2 + -7x2 = 0
28 + -27x + -7x2 = 0

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

Divide each side by '-7'.
-4 + 3.857142857x + x2 = 0

Move the constant term to the right:

Add '4' to each side of the equation.
-4 + 3.857142857x + 4 + x2 = 0 + 4

Reorder the terms:
-4 + 4 + 3.857142857x + x2 = 0 + 4

Combine like terms: -4 + 4 = 0
0 + 3.857142857x + x2 = 0 + 4
3.857142857x + x2 = 0 + 4

Combine like terms: 0 + 4 = 4
3.857142857x + x2 = 4

The x term is 3.857142857x.  Take half its coefficient (1.928571429).
Square it (3.719387757) and add it to both sides.

Add '3.719387757' to each side of the equation.
3.857142857x + 3.719387757 + x2 = 4 + 3.719387757

Reorder the terms:
3.719387757 + 3.857142857x + x2 = 4 + 3.719387757

Combine like terms: 4 + 3.719387757 = 7.719387757
3.719387757 + 3.857142857x + x2 = 7.719387757

Factor a perfect square on the left side:
(x + 1.928571429)(x + 1.928571429) = 7.719387757

Calculate the square root of the right side: 2.77837862

Break this problem into two subproblems by setting 
(x + 1.928571429) equal to 2.77837862 and -2.77837862.

Subproblem 1

x + 1.928571429 = 2.77837862 Simplifying x + 1.928571429 = 2.77837862 Reorder the terms: 1.928571429 + x = 2.77837862 Solving 1.928571429 + x = 2.77837862 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.928571429' to each side of the equation. 1.928571429 + -1.928571429 + x = 2.77837862 + -1.928571429 Combine like terms: 1.928571429 + -1.928571429 = 0.000000000 0.000000000 + x = 2.77837862 + -1.928571429 x = 2.77837862 + -1.928571429 Combine like terms: 2.77837862 + -1.928571429 = 0.849807191 x = 0.849807191 Simplifying x = 0.849807191

Subproblem 2

x + 1.928571429 = -2.77837862 Simplifying x + 1.928571429 = -2.77837862 Reorder the terms: 1.928571429 + x = -2.77837862 Solving 1.928571429 + x = -2.77837862 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-1.928571429' to each side of the equation. 1.928571429 + -1.928571429 + x = -2.77837862 + -1.928571429 Combine like terms: 1.928571429 + -1.928571429 = 0.000000000 0.000000000 + x = -2.77837862 + -1.928571429 x = -2.77837862 + -1.928571429 Combine like terms: -2.77837862 + -1.928571429 = -4.706950049 x = -4.706950049 Simplifying x = -4.706950049

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.849807191, -4.706950049}

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