9y-3y(y+4)=18

Solution for 9y-3y(y+4)=18 equation:

Simplifying
9y + -3y(y + 4) = 18

Reorder the terms:
9y + -3y(4 + y) = 18
9y + (4 * -3y + y * -3y) = 18
9y + (-12y + -3y2) = 18

Combine like terms: 9y + -12y = -3y
-3y + -3y2 = 18

Solving
-3y + -3y2 = 18

Solving for variable 'y'.

Reorder the terms:
-18 + -3y + -3y2 = 18 + -18

Combine like terms: 18 + -18 = 0
-18 + -3y + -3y2 = 0

Factor out the Greatest Common Factor (GCF), '-3'.
-3(6 + y + y2) = 0

Ignore the factor -3.
Subproblem 1
Set the factor '(6 + y + y2)' equal to zero and attempt to solve:

Simplifying
6 + y + y2 = 0

Solving
6 + y + y2 = 0

Begin completing the square.

Move the constant term to the right:

Add '-6' to each side of the equation.
6 + y + -6 + y2 = 0 + -6

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

Combine like terms: 6 + -6 = 0
0 + y + y2 = 0 + -6
y + y2 = 0 + -6

Combine like terms: 0 + -6 = -6
y + y2 = -6

The y term is y.  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.
y + 0.25 + y2 = -6 + 0.25

Reorder the terms:
0.25 + y + y2 = -6 + 0.25

Combine like terms: -6 + 0.25 = -5.75
0.25 + y + y2 = -5.75

Factor a perfect square on the left side:
(y + 0.5)(y + 0.5) = -5.75

Can't calculate square root of the right side.

The solution to this equation could not be determined.

This subproblem is being ignored because a solution could not be determined.

The solution to this equation could not be determined.