1)c²d-c³d=c²d*(1-c)
4m⁴-m²= m²*(4m²-1)
2)3a²b²-12a³b=3a²b(b-4a)
-21xy-14x²y = -7xy*(3+2x)
3)s²t-2st+s³t²= st*(s-2+s²t)
8m³-24m²-16m=8m*(m²-3m-2)