2h-20=(h+4)(h-4)

Solution for 2h-20=(h+4)(h-4) equation:

Simplifying
2h + -20 = (h + 4)(h + -4)

Reorder the terms:
-20 + 2h = (h + 4)(h + -4)

Reorder the terms:
-20 + 2h = (4 + h)(h + -4)

Reorder the terms:
-20 + 2h = (4 + h)(-4 + h)

Multiply (4 + h) * (-4 + h)
-20 + 2h = (4(-4 + h) + h(-4 + h))
-20 + 2h = ((-4 * 4 + h * 4) + h(-4 + h))
-20 + 2h = ((-16 + 4h) + h(-4 + h))
-20 + 2h = (-16 + 4h + (-4 * h + h * h))
-20 + 2h = (-16 + 4h + (-4h + h2))

Combine like terms: 4h + -4h = 0
-20 + 2h = (-16 + 0 + h2)
-20 + 2h = (-16 + h2)

Solving
-20 + 2h = -16 + h2

Solving for variable 'h'.

Reorder the terms:
-20 + 16 + 2h + -1h2 = -16 + h2 + 16 + -1h2

Combine like terms: -20 + 16 = -4
-4 + 2h + -1h2 = -16 + h2 + 16 + -1h2

Reorder the terms:
-4 + 2h + -1h2 = -16 + 16 + h2 + -1h2

Combine like terms: -16 + 16 = 0
-4 + 2h + -1h2 = 0 + h2 + -1h2
-4 + 2h + -1h2 = h2 + -1h2

Combine like terms: h2 + -1h2 = 0
-4 + 2h + -1h2 = 0

Begin completing the square.  Divide all terms by
-1 the coefficient of the squared term: 

Divide each side by '-1'.
4 + -2h + h2 = 0

Move the constant term to the right:

Add '-4' to each side of the equation.
4 + -2h + -4 + h2 = 0 + -4

Reorder the terms:
4 + -4 + -2h + h2 = 0 + -4

Combine like terms: 4 + -4 = 0
0 + -2h + h2 = 0 + -4
-2h + h2 = 0 + -4

Combine like terms: 0 + -4 = -4
-2h + h2 = -4

The h term is -2h.  Take half its coefficient (-1).
Square it (1) and add it to both sides.

Add '1' to each side of the equation.
-2h + 1 + h2 = -4 + 1

Reorder the terms:
1 + -2h + h2 = -4 + 1

Combine like terms: -4 + 1 = -3
1 + -2h + h2 = -3

Factor a perfect square on the left side:
(h + -1)(h + -1) = -3

Can't calculate square root of the right side.

The solution to this equation could not be determined.