9d^2-7d-8=0

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


Simplifying
9d2 + -7d + -8 = 0

Reorder the terms:
-8 + -7d + 9d2 = 0

Solving
-8 + -7d + 9d2 = 0

Solving for variable 'd'.

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

Divide each side by '9'.
-0.8888888889 + -0.7777777778d + d2 = 0

Move the constant term to the right:

Add '0.8888888889' to each side of the equation.
-0.8888888889 + -0.7777777778d + 0.8888888889 + d2 = 0 + 0.8888888889

Reorder the terms:
-0.8888888889 + 0.8888888889 + -0.7777777778d + d2 = 0 + 0.8888888889

Combine like terms: -0.8888888889 + 0.8888888889 = 0.0000000000
0.0000000000 + -0.7777777778d + d2 = 0 + 0.8888888889
-0.7777777778d + d2 = 0 + 0.8888888889

Combine like terms: 0 + 0.8888888889 = 0.8888888889
-0.7777777778d + d2 = 0.8888888889

The d term is -0.7777777778d.  Take half its coefficient (-0.3888888889).
Square it (0.1512345679) and add it to both sides.

Add '0.1512345679' to each side of the equation.
-0.7777777778d + 0.1512345679 + d2 = 0.8888888889 + 0.1512345679

Reorder the terms:
0.1512345679 + -0.7777777778d + d2 = 0.8888888889 + 0.1512345679

Combine like terms: 0.8888888889 + 0.1512345679 = 1.0401234568
0.1512345679 + -0.7777777778d + d2 = 1.0401234568

Factor a perfect square on the left side:
(d + -0.3888888889)(d + -0.3888888889) = 1.0401234568

Calculate the square root of the right side: 1.019864431

Break this problem into two subproblems by setting 
(d + -0.3888888889) equal to 1.019864431 and -1.019864431.

Subproblem 1

d + -0.3888888889 = 1.019864431 Simplifying d + -0.3888888889 = 1.019864431 Reorder the terms: -0.3888888889 + d = 1.019864431 Solving -0.3888888889 + d = 1.019864431 Solving for variable 'd'. Move all terms containing d to the left, all other terms to the right. Add '0.3888888889' to each side of the equation. -0.3888888889 + 0.3888888889 + d = 1.019864431 + 0.3888888889 Combine like terms: -0.3888888889 + 0.3888888889 = 0.0000000000 0.0000000000 + d = 1.019864431 + 0.3888888889 d = 1.019864431 + 0.3888888889 Combine like terms: 1.019864431 + 0.3888888889 = 1.4087533199 d = 1.4087533199 Simplifying d = 1.4087533199

Subproblem 2

d + -0.3888888889 = -1.019864431 Simplifying d + -0.3888888889 = -1.019864431 Reorder the terms: -0.3888888889 + d = -1.019864431 Solving -0.3888888889 + d = -1.019864431 Solving for variable 'd'. Move all terms containing d to the left, all other terms to the right. Add '0.3888888889' to each side of the equation. -0.3888888889 + 0.3888888889 + d = -1.019864431 + 0.3888888889 Combine like terms: -0.3888888889 + 0.3888888889 = 0.0000000000 0.0000000000 + d = -1.019864431 + 0.3888888889 d = -1.019864431 + 0.3888888889 Combine like terms: -1.019864431 + 0.3888888889 = -0.6309755421 d = -0.6309755421 Simplifying d = -0.6309755421

Solution

The solution to the problem is based on the solutions from the subproblems. d = {1.4087533199, -0.6309755421}

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