-7x^2+9x+8=0

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Solution for -7x^2+9x+8=0 equation:


Simplifying
-7x2 + 9x + 8 = 0

Reorder the terms:
8 + 9x + -7x2 = 0

Solving
8 + 9x + -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'.
-1.142857143 + -1.285714286x + x2 = 0

Move the constant term to the right:

Add '1.142857143' to each side of the equation.
-1.142857143 + -1.285714286x + 1.142857143 + x2 = 0 + 1.142857143

Reorder the terms:
-1.142857143 + 1.142857143 + -1.285714286x + x2 = 0 + 1.142857143

Combine like terms: -1.142857143 + 1.142857143 = 0.000000000
0.000000000 + -1.285714286x + x2 = 0 + 1.142857143
-1.285714286x + x2 = 0 + 1.142857143

Combine like terms: 0 + 1.142857143 = 1.142857143
-1.285714286x + x2 = 1.142857143

The x term is -1.285714286x.  Take half its coefficient (-0.642857143).
Square it (0.4132653063) and add it to both sides.

Add '0.4132653063' to each side of the equation.
-1.285714286x + 0.4132653063 + x2 = 1.142857143 + 0.4132653063

Reorder the terms:
0.4132653063 + -1.285714286x + x2 = 1.142857143 + 0.4132653063

Combine like terms: 1.142857143 + 0.4132653063 = 1.5561224493
0.4132653063 + -1.285714286x + x2 = 1.5561224493

Factor a perfect square on the left side:
(x + -0.642857143)(x + -0.642857143) = 1.5561224493

Calculate the square root of the right side: 1.247446371

Break this problem into two subproblems by setting 
(x + -0.642857143) equal to 1.247446371 and -1.247446371.

Subproblem 1

x + -0.642857143 = 1.247446371 Simplifying x + -0.642857143 = 1.247446371 Reorder the terms: -0.642857143 + x = 1.247446371 Solving -0.642857143 + x = 1.247446371 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.642857143' to each side of the equation. -0.642857143 + 0.642857143 + x = 1.247446371 + 0.642857143 Combine like terms: -0.642857143 + 0.642857143 = 0.000000000 0.000000000 + x = 1.247446371 + 0.642857143 x = 1.247446371 + 0.642857143 Combine like terms: 1.247446371 + 0.642857143 = 1.890303514 x = 1.890303514 Simplifying x = 1.890303514

Subproblem 2

x + -0.642857143 = -1.247446371 Simplifying x + -0.642857143 = -1.247446371 Reorder the terms: -0.642857143 + x = -1.247446371 Solving -0.642857143 + x = -1.247446371 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '0.642857143' to each side of the equation. -0.642857143 + 0.642857143 + x = -1.247446371 + 0.642857143 Combine like terms: -0.642857143 + 0.642857143 = 0.000000000 0.000000000 + x = -1.247446371 + 0.642857143 x = -1.247446371 + 0.642857143 Combine like terms: -1.247446371 + 0.642857143 = -0.604589228 x = -0.604589228 Simplifying x = -0.604589228

Solution

The solution to the problem is based on the solutions from the subproblems. x = {1.890303514, -0.604589228}

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