20a^2-43a+21=0

Solution for 20a^2-43a+21=0 equation:

Simplifying
20a2 + -43a + 21 = 0

Reorder the terms:
21 + -43a + 20a2 = 0

Solving
21 + -43a + 20a2 = 0

Solving for variable 'a'.

Factor a trinomial.
(3 + -4a)(7 + -5a) = 0

Subproblem 1
Set the factor '(3 + -4a)' equal to zero and attempt to solve:

Simplifying
3 + -4a = 0

Solving
3 + -4a = 0

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

Add '-3' to each side of the equation.
3 + -3 + -4a = 0 + -3

Combine like terms: 3 + -3 = 0
0 + -4a = 0 + -3
-4a = 0 + -3

Combine like terms: 0 + -3 = -3
-4a = -3

Divide each side by '-4'.
a = 0.75

Simplifying
a = 0.75
Subproblem 2
Set the factor '(7 + -5a)' equal to zero and attempt to solve:

Simplifying
7 + -5a = 0

Solving
7 + -5a = 0

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

Add '-7' to each side of the equation.
7 + -7 + -5a = 0 + -7

Combine like terms: 7 + -7 = 0
0 + -5a = 0 + -7
-5a = 0 + -7

Combine like terms: 0 + -7 = -7
-5a = -7

Divide each side by '-5'.
a = 1.4

Simplifying
a = 1.4
Solution
a = {0.75, 1.4}