Question

Which binomial below is a factor of the polynomial 3a2+6a-2a-4?

Answer 1

Answer is = -2(1-2a)

Answer 2

One may note you're kinda missing the factors provided, but anyhow, it factors to

$\bf 3a^2+6a-2a-4\implies (3a^2+6a)-(2a+4) \\\\\\ 3a(a+2)~~-~~2(a+2)\implies \stackrel{common~factor}{(a+2)}[3a-2]$