7x^2+3x=8

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Solution for 7x^2+3x=8 equation:


Simplifying
7x2 + 3x = 8

Reorder the terms:
3x + 7x2 = 8

Solving
3x + 7x2 = 8

Solving for variable 'x'.

Reorder the terms:
-8 + 3x + 7x2 = 8 + -8

Combine like terms: 8 + -8 = 0
-8 + 3x + 7x2 = 0

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

Divide each side by '7'.
-1.142857143 + 0.4285714286x + x2 = 0

Move the constant term to the right:

Add '1.142857143' to each side of the equation.
-1.142857143 + 0.4285714286x + 1.142857143 + x2 = 0 + 1.142857143

Reorder the terms:
-1.142857143 + 1.142857143 + 0.4285714286x + x2 = 0 + 1.142857143

Combine like terms: -1.142857143 + 1.142857143 = 0.000000000
0.000000000 + 0.4285714286x + x2 = 0 + 1.142857143
0.4285714286x + x2 = 0 + 1.142857143

Combine like terms: 0 + 1.142857143 = 1.142857143
0.4285714286x + x2 = 1.142857143

The x term is 0.4285714286x.  Take half its coefficient (0.2142857143).
Square it (0.04591836735) and add it to both sides.

Add '0.04591836735' to each side of the equation.
0.4285714286x + 0.04591836735 + x2 = 1.142857143 + 0.04591836735

Reorder the terms:
0.04591836735 + 0.4285714286x + x2 = 1.142857143 + 0.04591836735

Combine like terms: 1.142857143 + 0.04591836735 = 1.18877551035
0.04591836735 + 0.4285714286x + x2 = 1.18877551035

Factor a perfect square on the left side:
(x + 0.2142857143)(x + 0.2142857143) = 1.18877551035

Calculate the square root of the right side: 1.090309823

Break this problem into two subproblems by setting 
(x + 0.2142857143) equal to 1.090309823 and -1.090309823.

Subproblem 1

x + 0.2142857143 = 1.090309823 Simplifying x + 0.2142857143 = 1.090309823 Reorder the terms: 0.2142857143 + x = 1.090309823 Solving 0.2142857143 + x = 1.090309823 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2142857143' to each side of the equation. 0.2142857143 + -0.2142857143 + x = 1.090309823 + -0.2142857143 Combine like terms: 0.2142857143 + -0.2142857143 = 0.0000000000 0.0000000000 + x = 1.090309823 + -0.2142857143 x = 1.090309823 + -0.2142857143 Combine like terms: 1.090309823 + -0.2142857143 = 0.8760241087 x = 0.8760241087 Simplifying x = 0.8760241087

Subproblem 2

x + 0.2142857143 = -1.090309823 Simplifying x + 0.2142857143 = -1.090309823 Reorder the terms: 0.2142857143 + x = -1.090309823 Solving 0.2142857143 + x = -1.090309823 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.2142857143' to each side of the equation. 0.2142857143 + -0.2142857143 + x = -1.090309823 + -0.2142857143 Combine like terms: 0.2142857143 + -0.2142857143 = 0.0000000000 0.0000000000 + x = -1.090309823 + -0.2142857143 x = -1.090309823 + -0.2142857143 Combine like terms: -1.090309823 + -0.2142857143 = -1.3045955373 x = -1.3045955373 Simplifying x = -1.3045955373

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.8760241087, -1.3045955373}

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