5u^2+4=-21u

Solution for 5u^2+4=-21u equation:

Simplifying
5u2 + 4 = -21u

Reorder the terms:
4 + 5u2 = -21u

Solving
4 + 5u2 = -21u

Solving for variable 'u'.

Reorder the terms:
4 + 21u + 5u2 = -21u + 21u

Combine like terms: -21u + 21u = 0
4 + 21u + 5u2 = 0

Factor a trinomial.
(4 + u)(1 + 5u) = 0

Subproblem 1
Set the factor '(4 + u)' equal to zero and attempt to solve:

Simplifying
4 + u = 0

Solving
4 + u = 0

Move all terms containing u to the left, all other terms to the right.

Add '-4' to each side of the equation.
4 + -4 + u = 0 + -4

Combine like terms: 4 + -4 = 0
0 + u = 0 + -4
u = 0 + -4

Combine like terms: 0 + -4 = -4
u = -4

Simplifying
u = -4
Subproblem 2
Set the factor '(1 + 5u)' equal to zero and attempt to solve:

Simplifying
1 + 5u = 0

Solving
1 + 5u = 0

Move all terms containing u to the left, all other terms to the right.

Add '-1' to each side of the equation.
1 + -1 + 5u = 0 + -1

Combine like terms: 1 + -1 = 0
0 + 5u = 0 + -1
5u = 0 + -1

Combine like terms: 0 + -1 = -1
5u = -1

Divide each side by '5'.
u = -0.2

Simplifying
u = -0.2
Solution
u = {-4, -0.2}