Question

How do you factor the expression `2x ^2 + 36x - 80`?

Answer 1

y = 2(x - 2)(x + 20).

Explanation:

`y = 2(x^2 + 18x - 40)`. Factor the trinomial in parentheses.
Find 2 numbers knowing sum (18) and product (-40). These numbers have opposite signs because ac < 0.
Factor pairs of (-40) ---> (-2, 20). This sum is 18 = b. Then the 2 numbers are: -2 and 20.
Factored form: y = 2(x - 2)(x + 20)