3u^2+2u-21=

Solution for 3u^2+2u-21= equation:

Simplifying
3u2 + 2u + -21 = 0

Reorder the terms:
-21 + 2u + 3u2 = 0

Solving
-21 + 2u + 3u2 = 0

Solving for variable 'u'.

Factor a trinomial.
(-3 + -1u)(7 + -3u) = 0

Subproblem 1
Set the factor '(-3 + -1u)' equal to zero and attempt to solve:

Simplifying
-3 + -1u = 0

Solving
-3 + -1u = 0

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

Add '3' to each side of the equation.
-3 + 3 + -1u = 0 + 3

Combine like terms: -3 + 3 = 0
0 + -1u = 0 + 3
-1u = 0 + 3

Combine like terms: 0 + 3 = 3
-1u = 3

Divide each side by '-1'.
u = -3

Simplifying
u = -3
Subproblem 2
Set the factor '(7 + -3u)' equal to zero and attempt to solve:

Simplifying
7 + -3u = 0

Solving
7 + -3u = 0

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

Add '-7' to each side of the equation.
7 + -7 + -3u = 0 + -7

Combine like terms: 7 + -7 = 0
0 + -3u = 0 + -7
-3u = 0 + -7

Combine like terms: 0 + -7 = -7
-3u = -7

Divide each side by '-3'.
u = 2.333333333

Simplifying
u = 2.333333333
Solution
u = {-3, 2.333333333}