2d^2-18d-7=0

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Solution for 2d^2-18d-7=0 equation:


Simplifying
2d2 + -18d + -7 = 0

Reorder the terms:
-7 + -18d + 2d2 = 0

Solving
-7 + -18d + 2d2 = 0

Solving for variable 'd'.

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

Divide each side by '2'.
-3.5 + -9d + d2 = 0

Move the constant term to the right:

Add '3.5' to each side of the equation.
-3.5 + -9d + 3.5 + d2 = 0 + 3.5

Reorder the terms:
-3.5 + 3.5 + -9d + d2 = 0 + 3.5

Combine like terms: -3.5 + 3.5 = 0.0
0.0 + -9d + d2 = 0 + 3.5
-9d + d2 = 0 + 3.5

Combine like terms: 0 + 3.5 = 3.5
-9d + d2 = 3.5

The d term is -9d.  Take half its coefficient (-4.5).
Square it (20.25) and add it to both sides.

Add '20.25' to each side of the equation.
-9d + 20.25 + d2 = 3.5 + 20.25

Reorder the terms:
20.25 + -9d + d2 = 3.5 + 20.25

Combine like terms: 3.5 + 20.25 = 23.75
20.25 + -9d + d2 = 23.75

Factor a perfect square on the left side:
(d + -4.5)(d + -4.5) = 23.75

Calculate the square root of the right side: 4.873397172

Break this problem into two subproblems by setting 
(d + -4.5) equal to 4.873397172 and -4.873397172.

Subproblem 1

d + -4.5 = 4.873397172 Simplifying d + -4.5 = 4.873397172 Reorder the terms: -4.5 + d = 4.873397172 Solving -4.5 + d = 4.873397172 Solving for variable 'd'. Move all terms containing d to the left, all other terms to the right. Add '4.5' to each side of the equation. -4.5 + 4.5 + d = 4.873397172 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + d = 4.873397172 + 4.5 d = 4.873397172 + 4.5 Combine like terms: 4.873397172 + 4.5 = 9.373397172 d = 9.373397172 Simplifying d = 9.373397172

Subproblem 2

d + -4.5 = -4.873397172 Simplifying d + -4.5 = -4.873397172 Reorder the terms: -4.5 + d = -4.873397172 Solving -4.5 + d = -4.873397172 Solving for variable 'd'. Move all terms containing d to the left, all other terms to the right. Add '4.5' to each side of the equation. -4.5 + 4.5 + d = -4.873397172 + 4.5 Combine like terms: -4.5 + 4.5 = 0.0 0.0 + d = -4.873397172 + 4.5 d = -4.873397172 + 4.5 Combine like terms: -4.873397172 + 4.5 = -0.373397172 d = -0.373397172 Simplifying d = -0.373397172

Solution

The solution to the problem is based on the solutions from the subproblems. d = {9.373397172, -0.373397172}

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