Which shows one way to determine the factors of 4x3 + x2 – 8x – 2 by grouping? x24x + 1 – 24x + 1 x24x – 1 + 24x – 1 4x2x + 2 – 1x + 2 4x2x – 2 – 1x – 2

Looking at   4x3 + x2 – 8x – 2, I see immediately that x^2 can be facto out of the first 2 terms => 4x^2(x+1)and -2 out of the last 2 terms => -2(4x+1).Notice how the factor (4x+1) shows up twice.We can factor this (4x+1) out, obtaining   (x^2 - 2) (4x+1).  These are the desi factors, found "by grouping."