Question

2mn^2-19mn-21m

Answer 1

m(2n^2 - 19n -21)
m(2n^2 +2n -21n -21)
m(2n(n+1) -21(n+1))
m(2n-21)(n+1)

Answer 2

thank you

Answer 3

12r^2+4r-8 my answer is 4(3r-2)(r+1)