5x^2+8x-9=0

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Solution for 5x^2+8x-9=0 equation:


Simplifying
5x2 + 8x + -9 = 0

Reorder the terms:
-9 + 8x + 5x2 = 0

Solving
-9 + 8x + 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'.
-1.8 + 1.6x + x2 = 0

Move the constant term to the right:

Add '1.8' to each side of the equation.
-1.8 + 1.6x + 1.8 + x2 = 0 + 1.8

Reorder the terms:
-1.8 + 1.8 + 1.6x + x2 = 0 + 1.8

Combine like terms: -1.8 + 1.8 = 0.0
0.0 + 1.6x + x2 = 0 + 1.8
1.6x + x2 = 0 + 1.8

Combine like terms: 0 + 1.8 = 1.8
1.6x + x2 = 1.8

The x term is 1.6x.  Take half its coefficient (0.8).
Square it (0.64) and add it to both sides.

Add '0.64' to each side of the equation.
1.6x + 0.64 + x2 = 1.8 + 0.64

Reorder the terms:
0.64 + 1.6x + x2 = 1.8 + 0.64

Combine like terms: 1.8 + 0.64 = 2.44
0.64 + 1.6x + x2 = 2.44

Factor a perfect square on the left side:
(x + 0.8)(x + 0.8) = 2.44

Calculate the square root of the right side: 1.562049935

Break this problem into two subproblems by setting 
(x + 0.8) equal to 1.562049935 and -1.562049935.

Subproblem 1

x + 0.8 = 1.562049935 Simplifying x + 0.8 = 1.562049935 Reorder the terms: 0.8 + x = 1.562049935 Solving 0.8 + x = 1.562049935 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.8' to each side of the equation. 0.8 + -0.8 + x = 1.562049935 + -0.8 Combine like terms: 0.8 + -0.8 = 0.0 0.0 + x = 1.562049935 + -0.8 x = 1.562049935 + -0.8 Combine like terms: 1.562049935 + -0.8 = 0.762049935 x = 0.762049935 Simplifying x = 0.762049935

Subproblem 2

x + 0.8 = -1.562049935 Simplifying x + 0.8 = -1.562049935 Reorder the terms: 0.8 + x = -1.562049935 Solving 0.8 + x = -1.562049935 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '-0.8' to each side of the equation. 0.8 + -0.8 + x = -1.562049935 + -0.8 Combine like terms: 0.8 + -0.8 = 0.0 0.0 + x = -1.562049935 + -0.8 x = -1.562049935 + -0.8 Combine like terms: -1.562049935 + -0.8 = -2.362049935 x = -2.362049935 Simplifying x = -2.362049935

Solution

The solution to the problem is based on the solutions from the subproblems. x = {0.762049935, -2.362049935}

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