4u^2-9u+36u+81=0

Solution for 4u^2-9u+36u+81=0 equation:

Simplifying
4u2 + -9u + 36u + 81 = 0

Reorder the terms:
81 + -9u + 36u + 4u2 = 0

Combine like terms: -9u + 36u = 27u
81 + 27u + 4u2 = 0

Solving
81 + 27u + 4u2 = 0

Solving for variable 'u'.

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

Divide each side by '4'.
20.25 + 6.75u + u2 = 0

Move the constant term to the right:

Add '-20.25' to each side of the equation.
20.25 + 6.75u + -20.25 + u2 = 0 + -20.25

Reorder the terms:
20.25 + -20.25 + 6.75u + u2 = 0 + -20.25

Combine like terms: 20.25 + -20.25 = 0.00
0.00 + 6.75u + u2 = 0 + -20.25
6.75u + u2 = 0 + -20.25

Combine like terms: 0 + -20.25 = -20.25
6.75u + u2 = -20.25

The u term is 6.75u.  Take half its coefficient (3.375).
Square it (11.390625) and add it to both sides.

Add '11.390625' to each side of the equation.
6.75u + 11.390625 + u2 = -20.25 + 11.390625

Reorder the terms:
11.390625 + 6.75u + u2 = -20.25 + 11.390625

Combine like terms: -20.25 + 11.390625 = -8.859375
11.390625 + 6.75u + u2 = -8.859375

Factor a perfect square on the left side:
(u + 3.375)(u + 3.375) = -8.859375

Can't calculate square root of the right side.

The solution to this equation could not be determined.