9y-81-(y+6)(y-5)=

Solution for 9y-81-(y+6)(y-5)= equation:

Simplifying
9y + -81 + -1(y + 6)(y + -5) = 0

Reorder the terms:
9y + -81 + -1(6 + y)(y + -5) = 0

Reorder the terms:
9y + -81 + -1(6 + y)(-5 + y) = 0

Multiply (6 + y) * (-5 + y)
9y + -81 + -1(6(-5 + y) + y(-5 + y)) = 0
9y + -81 + -1((-5 * 6 + y * 6) + y(-5 + y)) = 0
9y + -81 + -1((-30 + 6y) + y(-5 + y)) = 0
9y + -81 + -1(-30 + 6y + (-5 * y + y * y)) = 0
9y + -81 + -1(-30 + 6y + (-5y + y2)) = 0

Combine like terms: 6y + -5y = 1y
9y + -81 + -1(-30 + 1y + y2) = 0
9y + -81 + (-30 * -1 + 1y * -1 + y2 * -1) = 0
9y + -81 + (30 + -1y + -1y2) = 0

Reorder the terms:
-81 + 30 + 9y + -1y + -1y2 = 0

Combine like terms: -81 + 30 = -51
-51 + 9y + -1y + -1y2 = 0

Combine like terms: 9y + -1y = 8y
-51 + 8y + -1y2 = 0

Solving
-51 + 8y + -1y2 = 0

Solving for variable 'y'.

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
51 + -8y + y2 = 0

Move the constant term to the right:

Add '-51' to each side of the equation.
51 + -8y + -51 + y2 = 0 + -51

Reorder the terms:
51 + -51 + -8y + y2 = 0 + -51

Combine like terms: 51 + -51 = 0
0 + -8y + y2 = 0 + -51
-8y + y2 = 0 + -51

Combine like terms: 0 + -51 = -51
-8y + y2 = -51

The y term is -8y.  Take half its coefficient (-4).
Square it (16) and add it to both sides.

Add '16' to each side of the equation.
-8y + 16 + y2 = -51 + 16

Reorder the terms:
16 + -8y + y2 = -51 + 16

Combine like terms: -51 + 16 = -35
16 + -8y + y2 = -35

Factor a perfect square on the left side:
(y + -4)(y + -4) = -35

Can't calculate square root of the right side.

The solution to this equation could not be determined.