5y^2-21y-20=

Solution for 5y^2-21y-20= equation:

Simplifying
5y2 + -21y + -20 = 0

Reorder the terms:
-20 + -21y + 5y2 = 0

Solving
-20 + -21y + 5y2 = 0

Solving for variable 'y'.

Factor a trinomial.
(-4 + -5y)(5 + -1y) = 0

Subproblem 1
Set the factor '(-4 + -5y)' equal to zero and attempt to solve:

Simplifying
-4 + -5y = 0

Solving
-4 + -5y = 0

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

Add '4' to each side of the equation.
-4 + 4 + -5y = 0 + 4

Combine like terms: -4 + 4 = 0
0 + -5y = 0 + 4
-5y = 0 + 4

Combine like terms: 0 + 4 = 4
-5y = 4

Divide each side by '-5'.
y = -0.8

Simplifying
y = -0.8
Subproblem 2
Set the factor '(5 + -1y)' equal to zero and attempt to solve:

Simplifying
5 + -1y = 0

Solving
5 + -1y = 0

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

Add '-5' to each side of the equation.
5 + -5 + -1y = 0 + -5

Combine like terms: 5 + -5 = 0
0 + -1y = 0 + -5
-1y = 0 + -5

Combine like terms: 0 + -5 = -5
-1y = -5

Divide each side by '-1'.
y = 5

Simplifying
y = 5
Solution
y = {-0.8, 5}