-7d^2+7d+8=0

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


Simplifying
-7d2 + 7d + 8 = 0

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

Solving
8 + 7d + -7d2 = 0

Solving for variable 'd'.

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

Divide each side by '-7'.
-1.142857143 + -1d + d2 = 0

Move the constant term to the right:

Add '1.142857143' to each side of the equation.
-1.142857143 + -1d + 1.142857143 + d2 = 0 + 1.142857143

Reorder the terms:
-1.142857143 + 1.142857143 + -1d + d2 = 0 + 1.142857143

Combine like terms: -1.142857143 + 1.142857143 = 0.000000000
0.000000000 + -1d + d2 = 0 + 1.142857143
-1d + d2 = 0 + 1.142857143

Combine like terms: 0 + 1.142857143 = 1.142857143
-1d + d2 = 1.142857143

The d term is -1d.  Take half its coefficient (-0.5).
Square it (0.25) and add it to both sides.

Add '0.25' to each side of the equation.
-1d + 0.25 + d2 = 1.142857143 + 0.25

Reorder the terms:
0.25 + -1d + d2 = 1.142857143 + 0.25

Combine like terms: 1.142857143 + 0.25 = 1.392857143
0.25 + -1d + d2 = 1.392857143

Factor a perfect square on the left side:
(d + -0.5)(d + -0.5) = 1.392857143

Calculate the square root of the right side: 1.180193689

Break this problem into two subproblems by setting 
(d + -0.5) equal to 1.180193689 and -1.180193689.

Subproblem 1

d + -0.5 = 1.180193689 Simplifying d + -0.5 = 1.180193689 Reorder the terms: -0.5 + d = 1.180193689 Solving -0.5 + d = 1.180193689 Solving for variable 'd'. Move all terms containing d to the left, all other terms to the right. Add '0.5' to each side of the equation. -0.5 + 0.5 + d = 1.180193689 + 0.5 Combine like terms: -0.5 + 0.5 = 0.0 0.0 + d = 1.180193689 + 0.5 d = 1.180193689 + 0.5 Combine like terms: 1.180193689 + 0.5 = 1.680193689 d = 1.680193689 Simplifying d = 1.680193689

Subproblem 2

d + -0.5 = -1.180193689 Simplifying d + -0.5 = -1.180193689 Reorder the terms: -0.5 + d = -1.180193689 Solving -0.5 + d = -1.180193689 Solving for variable 'd'. Move all terms containing d to the left, all other terms to the right. Add '0.5' to each side of the equation. -0.5 + 0.5 + d = -1.180193689 + 0.5 Combine like terms: -0.5 + 0.5 = 0.0 0.0 + d = -1.180193689 + 0.5 d = -1.180193689 + 0.5 Combine like terms: -1.180193689 + 0.5 = -0.680193689 d = -0.680193689 Simplifying d = -0.680193689

Solution

The solution to the problem is based on the solutions from the subproblems. d = {1.680193689, -0.680193689}

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