h^2+10h+21=0

Solution for h^2+10h+21=0 equation:

Simplifying
h2 + 10h + 21 = 0

Reorder the terms:
21 + 10h + h2 = 0

Solving
21 + 10h + h2 = 0

Solving for variable 'h'.

Factor a trinomial.
(7 + h)(3 + h) = 0

Subproblem 1
Set the factor '(7 + h)' equal to zero and attempt to solve:

Simplifying
7 + h = 0

Solving
7 + h = 0

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

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

Combine like terms: 7 + -7 = 0
0 + h = 0 + -7
h = 0 + -7

Combine like terms: 0 + -7 = -7
h = -7

Simplifying
h = -7
Subproblem 2
Set the factor '(3 + h)' equal to zero and attempt to solve:

Simplifying
3 + h = 0

Solving
3 + h = 0

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

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

Combine like terms: 3 + -3 = 0
0 + h = 0 + -3
h = 0 + -3

Combine like terms: 0 + -3 = -3
h = -3

Simplifying
h = -3
Solution
h = {-7, -3}