How do you factor completely: #10x^2 + 2x − 8#?

1 Answer
Jul 12, 2015

Answer:

Factor: #y = 10x^2 + 2x - 8#

Explanation:

In this case, use the shortcut, since (a - b + c) = 0. One factor is (x + 1) and the other is (x + c/a = - 8/10).
y = (x + 1)(10x - 8) = 2(x + 1)(5x - 4)

You may also use the new AC Method.
Converted #y' = x^2 + 2x - 80 = (x - p')(x - q').#
Factor pairs of (-80) -> ...(-4, 20)(-8, 10). This sum is 2 = b. Then p' = -8 and q' = 10.
Then, #p = (p')/a = --8/10# and #q = (q')/a = 10/10 = 1.#

y = 10(x - 8/10)(x + 1) = (10x - 8)(x + 1)= 2(5x - 4)(x + 1)