a^2+3a-21=33

Solution for a^2+3a-21=33 equation:

Simplifying
a2 + 3a + -21 = 33

Reorder the terms:
-21 + 3a + a2 = 33

Solving
-21 + 3a + a2 = 33

Solving for variable 'a'.

Reorder the terms:
-21 + -33 + 3a + a2 = 33 + -33

Combine like terms: -21 + -33 = -54
-54 + 3a + a2 = 33 + -33

Combine like terms: 33 + -33 = 0
-54 + 3a + a2 = 0

Factor a trinomial.
(-9 + -1a)(6 + -1a) = 0

Subproblem 1
Set the factor '(-9 + -1a)' equal to zero and attempt to solve:

Simplifying
-9 + -1a = 0

Solving
-9 + -1a = 0

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

Add '9' to each side of the equation.
-9 + 9 + -1a = 0 + 9

Combine like terms: -9 + 9 = 0
0 + -1a = 0 + 9
-1a = 0 + 9

Combine like terms: 0 + 9 = 9
-1a = 9

Divide each side by '-1'.
a = -9

Simplifying
a = -9
Subproblem 2
Set the factor '(6 + -1a)' equal to zero and attempt to solve:

Simplifying
6 + -1a = 0

Solving
6 + -1a = 0

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

Add '-6' to each side of the equation.
6 + -6 + -1a = 0 + -6

Combine like terms: 6 + -6 = 0
0 + -1a = 0 + -6
-1a = 0 + -6

Combine like terms: 0 + -6 = -6
-1a = -6

Divide each side by '-1'.
a = 6

Simplifying
a = 6
Solution
a = {-9, 6}