2y^2-6y-9=0

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Solution for 2y^2-6y-9=0 equation:


Simplifying
2y2 + -6y + -9 = 0

Reorder the terms:
-9 + -6y + 2y2 = 0

Solving
-9 + -6y + 2y2 = 0

Solving for variable 'y'.

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

Divide each side by '2'.
-4.5 + -3y + y2 = 0

Move the constant term to the right:

Add '4.5' to each side of the equation.
-4.5 + -3y + 4.5 + y2 = 0 + 4.5

Reorder the terms:
-4.5 + 4.5 + -3y + y2 = 0 + 4.5

Combine like terms: -4.5 + 4.5 = 0.0
0.0 + -3y + y2 = 0 + 4.5
-3y + y2 = 0 + 4.5

Combine like terms: 0 + 4.5 = 4.5
-3y + y2 = 4.5

The y term is -3y.  Take half its coefficient (-1.5).
Square it (2.25) and add it to both sides.

Add '2.25' to each side of the equation.
-3y + 2.25 + y2 = 4.5 + 2.25

Reorder the terms:
2.25 + -3y + y2 = 4.5 + 2.25

Combine like terms: 4.5 + 2.25 = 6.75
2.25 + -3y + y2 = 6.75

Factor a perfect square on the left side:
(y + -1.5)(y + -1.5) = 6.75

Calculate the square root of the right side: 2.598076211

Break this problem into two subproblems by setting 
(y + -1.5) equal to 2.598076211 and -2.598076211.

Subproblem 1

y + -1.5 = 2.598076211 Simplifying y + -1.5 = 2.598076211 Reorder the terms: -1.5 + y = 2.598076211 Solving -1.5 + y = 2.598076211 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '1.5' to each side of the equation. -1.5 + 1.5 + y = 2.598076211 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + y = 2.598076211 + 1.5 y = 2.598076211 + 1.5 Combine like terms: 2.598076211 + 1.5 = 4.098076211 y = 4.098076211 Simplifying y = 4.098076211

Subproblem 2

y + -1.5 = -2.598076211 Simplifying y + -1.5 = -2.598076211 Reorder the terms: -1.5 + y = -2.598076211 Solving -1.5 + y = -2.598076211 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '1.5' to each side of the equation. -1.5 + 1.5 + y = -2.598076211 + 1.5 Combine like terms: -1.5 + 1.5 = 0.0 0.0 + y = -2.598076211 + 1.5 y = -2.598076211 + 1.5 Combine like terms: -2.598076211 + 1.5 = -1.098076211 y = -1.098076211 Simplifying y = -1.098076211

Solution

The solution to the problem is based on the solutions from the subproblems. y = {4.098076211, -1.098076211}

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