5a^2-4a-28=0

Solution for 5a^2-4a-28=0 equation:

Simplifying
5a2 + -4a + -28 = 0

Reorder the terms:
-28 + -4a + 5a2 = 0

Solving
-28 + -4a + 5a2 = 0

Solving for variable 'a'.

Factor a trinomial.
(-2 + -1a)(14 + -5a) = 0

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

Simplifying
-2 + -1a = 0

Solving
-2 + -1a = 0

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

Add '2' to each side of the equation.
-2 + 2 + -1a = 0 + 2

Combine like terms: -2 + 2 = 0
0 + -1a = 0 + 2
-1a = 0 + 2

Combine like terms: 0 + 2 = 2
-1a = 2

Divide each side by '-1'.
a = -2

Simplifying
a = -2
Subproblem 2
Set the factor '(14 + -5a)' equal to zero and attempt to solve:

Simplifying
14 + -5a = 0

Solving
14 + -5a = 0

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

Add '-14' to each side of the equation.
14 + -14 + -5a = 0 + -14

Combine like terms: 14 + -14 = 0
0 + -5a = 0 + -14
-5a = 0 + -14

Combine like terms: 0 + -14 = -14
-5a = -14

Divide each side by '-5'.
a = 2.8

Simplifying
a = 2.8
Solution
a = {-2, 2.8}