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

Jun 25, 2016

$2 \left({x}^{2} - x - 42\right)$

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 $2 \left({x}^{2} - x - 42\right)$.

Double checking our work
$2 \left({x}^{2}\right) = 2 {x}^{2}$
$2 \left(x\right) = 2 x$
$2 \left(42\right) = 8$

Therefore = $2 {x}^{2} - 2 x - 84$

Jun 25, 2016

2(x + 6)(x - 7)

Explanation:

$y = 2 \left({x}^{2} - x - 42\right) .$
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)