12a^2-5a^2-28=0

Solution for 12a^2-5a^2-28=0 equation:

Simplifying
12a2 + -5a2 + -28 = 0

Reorder the terms:
-28 + 12a2 + -5a2 = 0

Combine like terms: 12a2 + -5a2 = 7a2
-28 + 7a2 = 0

Solving
-28 + 7a2 = 0

Solving for variable 'a'.

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

Add '28' to each side of the equation.
-28 + 28 + 7a2 = 0 + 28

Combine like terms: -28 + 28 = 0
0 + 7a2 = 0 + 28
7a2 = 0 + 28

Combine like terms: 0 + 28 = 28
7a2 = 28

Divide each side by '7'.
a2 = 4

Simplifying
a2 = 4

Take the square root of each side:
a = {-2, 2}