v^2-20v-21=0

Solution for v^2-20v-21=0 equation:

Simplifying
v2 + -20v + -21 = 0

Reorder the terms:
-21 + -20v + v2 = 0

Solving
-21 + -20v + v2 = 0

Solving for variable 'v'.

Factor a trinomial.
(-1 + -1v)(21 + -1v) = 0

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

Simplifying
-1 + -1v = 0

Solving
-1 + -1v = 0

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

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

Combine like terms: -1 + 1 = 0
0 + -1v = 0 + 1
-1v = 0 + 1

Combine like terms: 0 + 1 = 1
-1v = 1

Divide each side by '-1'.
v = -1

Simplifying
v = -1
Subproblem 2
Set the factor '(21 + -1v)' equal to zero and attempt to solve:

Simplifying
21 + -1v = 0

Solving
21 + -1v = 0

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

Add '-21' to each side of the equation.
21 + -21 + -1v = 0 + -21

Combine like terms: 21 + -21 = 0
0 + -1v = 0 + -21
-1v = 0 + -21

Combine like terms: 0 + -21 = -21
-1v = -21

Divide each side by '-1'.
v = 21

Simplifying
v = 21
Solution
v = {-1, 21}