-9(1-y)y+81(1-y)-1=0

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Solution for -9(1-y)y+81(1-y)-1=0 equation:


Simplifying
-9(1 + -1y) * y + 81(1 + -1y) + -1 = 0

Reorder the terms for easier multiplication:
-9y(1 + -1y) + 81(1 + -1y) + -1 = 0
(1 * -9y + -1y * -9y) + 81(1 + -1y) + -1 = 0
(-9y + 9y2) + 81(1 + -1y) + -1 = 0
-9y + 9y2 + (1 * 81 + -1y * 81) + -1 = 0
-9y + 9y2 + (81 + -81y) + -1 = 0

Reorder the terms:
81 + -1 + -9y + -81y + 9y2 = 0

Combine like terms: 81 + -1 = 80
80 + -9y + -81y + 9y2 = 0

Combine like terms: -9y + -81y = -90y
80 + -90y + 9y2 = 0

Solving
80 + -90y + 9y2 = 0

Solving for variable 'y'.

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

Divide each side by '9'.
8.888888889 + -10y + y2 = 0

Move the constant term to the right:

Add '-8.888888889' to each side of the equation.
8.888888889 + -10y + -8.888888889 + y2 = 0 + -8.888888889

Reorder the terms:
8.888888889 + -8.888888889 + -10y + y2 = 0 + -8.888888889

Combine like terms: 8.888888889 + -8.888888889 = 0.000000000
0.000000000 + -10y + y2 = 0 + -8.888888889
-10y + y2 = 0 + -8.888888889

Combine like terms: 0 + -8.888888889 = -8.888888889
-10y + y2 = -8.888888889

The y term is -10y.  Take half its coefficient (-5).
Square it (25) and add it to both sides.

Add '25' to each side of the equation.
-10y + 25 + y2 = -8.888888889 + 25

Reorder the terms:
25 + -10y + y2 = -8.888888889 + 25

Combine like terms: -8.888888889 + 25 = 16.111111111
25 + -10y + y2 = 16.111111111

Factor a perfect square on the left side:
(y + -5)(y + -5) = 16.111111111

Calculate the square root of the right side: 4.01386486

Break this problem into two subproblems by setting 
(y + -5) equal to 4.01386486 and -4.01386486.

Subproblem 1

y + -5 = 4.01386486 Simplifying y + -5 = 4.01386486 Reorder the terms: -5 + y = 4.01386486 Solving -5 + y = 4.01386486 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '5' to each side of the equation. -5 + 5 + y = 4.01386486 + 5 Combine like terms: -5 + 5 = 0 0 + y = 4.01386486 + 5 y = 4.01386486 + 5 Combine like terms: 4.01386486 + 5 = 9.01386486 y = 9.01386486 Simplifying y = 9.01386486

Subproblem 2

y + -5 = -4.01386486 Simplifying y + -5 = -4.01386486 Reorder the terms: -5 + y = -4.01386486 Solving -5 + y = -4.01386486 Solving for variable 'y'. Move all terms containing y to the left, all other terms to the right. Add '5' to each side of the equation. -5 + 5 + y = -4.01386486 + 5 Combine like terms: -5 + 5 = 0 0 + y = -4.01386486 + 5 y = -4.01386486 + 5 Combine like terms: -4.01386486 + 5 = 0.98613514 y = 0.98613514 Simplifying y = 0.98613514

Solution

The solution to the problem is based on the solutions from the subproblems. y = {9.01386486, 0.98613514}

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