I am asked to factorise 2x^2-6x-56.
I find two answers: 1. (2x+8)(x-7) and 2. (2x-14)(x+4).
I am told that the answer is actually 2(x^2-3x-28).
What have I done wrong? Is my mistake leaving a leading coefficient >1 (in both my answers, this being 2) in the brackets?