How do you factor 2x^2-2x-84?

2 Answers
Jun 25, 2016

2(x^2-x-42)

Explanation:

when factorising you find a common multiple of all the digits. In this case we have 2. x does not go into 84. We then use factorisation 2(x^2-x-42).

Double checking our work
2(x^2)= 2x^2
2(x)= 2x
2(42) = 8

Therefore = 2x^2-2x-84

Jun 25, 2016

2(x + 6)(x - 7)

Explanation:

y = 2(x^2 - x - 42).
Factor the trinomial in parentheses.
Find 2 numbers knowing their sum (b = -1) and their product (c = -42)
They are: 6 and -7.
Sum: 6 - 7 = -1
Product: 6(-7) = -42
y = 2(x + 6)(x - 7)