280=4(h+2)(h+5)

Solution for 280=4(h+2)(h+5) equation:

Simplifying
280 = 4(h + 2)(h + 5)

Reorder the terms:
280 = 4(2 + h)(h + 5)

Reorder the terms:
280 = 4(2 + h)(5 + h)

Multiply (2 + h) * (5 + h)
280 = 4(2(5 + h) + h(5 + h))
280 = 4((5 * 2 + h * 2) + h(5 + h))
280 = 4((10 + 2h) + h(5 + h))
280 = 4(10 + 2h + (5 * h + h * h))
280 = 4(10 + 2h + (5h + h2))

Combine like terms: 2h + 5h = 7h
280 = 4(10 + 7h + h2)
280 = (10 * 4 + 7h * 4 + h2 * 4)
280 = (40 + 28h + 4h2)

Solving
280 = 40 + 28h + 4h2

Solving for variable 'h'.

Combine like terms: 280 + -40 = 240
240 + -28h + -4h2 = 40 + 28h + 4h2 + -40 + -28h + -4h2

Reorder the terms:
240 + -28h + -4h2 = 40 + -40 + 28h + -28h + 4h2 + -4h2

Combine like terms: 40 + -40 = 0
240 + -28h + -4h2 = 0 + 28h + -28h + 4h2 + -4h2
240 + -28h + -4h2 = 28h + -28h + 4h2 + -4h2

Combine like terms: 28h + -28h = 0
240 + -28h + -4h2 = 0 + 4h2 + -4h2
240 + -28h + -4h2 = 4h2 + -4h2

Combine like terms: 4h2 + -4h2 = 0
240 + -28h + -4h2 = 0

Factor out the Greatest Common Factor (GCF), '4'.
4(60 + -7h + -1h2) = 0

Factor a trinomial.
4((5 + -1h)(12 + h)) = 0

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

Simplifying
5 + -1h = 0

Solving
5 + -1h = 0

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

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

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

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

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

Simplifying
h = 5
Subproblem 2
Set the factor '(12 + h)' equal to zero and attempt to solve:

Simplifying
12 + h = 0

Solving
12 + h = 0

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

Add '-12' to each side of the equation.
12 + -12 + h = 0 + -12

Combine like terms: 12 + -12 = 0
0 + h = 0 + -12
h = 0 + -12

Combine like terms: 0 + -12 = -12
h = -12

Simplifying
h = -12
Solution
h = {5, -12}