Question

Solve x^2 - 8x - 20 = 0.

Answer 1

http://gyazo.com/87f3289087152a7445485189c982bde3

Answer 2

find the factors of -20 that add to -8, the larger factor is negative and the smaller is positive

Answer 3

The left hand side factors into a product with two terms:
(x-10)(x+2)
You can split this into two equations: x-10=0 and x+2=0
just subtract two from both sides. :p