3(m+1)²-5(m+1)(m-1)+2(m-1)²
=3m²+6m+3-5(m²-1)+2m²-4m+2
=3m²+6m+3-5m²+5+2m²-4m+2
=3m²-5m²+2m²+6m-4m+3+5+2
=2m+10
=2*(-1)+10
=-2+10
=8