Question

Factor by grouping 2u^3+3u^2-14u-21

Answer 1

(2u³+3u²)-(14u+21)
u²(2u+3)-7(2u+3)
(u²-7)(2u+3)
(u+√7)(u-√7)(2u+3)

Answer 2

$\bf 2u^3+3u^2-14u-21\implies (2u^3+3u^2)-(14u+21) \\\\\\ u^2(2u+3)-7(2u+3)\implies \stackrel{\stackrel{common}{factor}}{(2u+3)}(u^2-7)$