16.18
1) 2m(m-6)²-m²(2m-15)=
=2m(m²-12m+36)-2m³+15m²=
=2m³-24m²+72m-2m³+15m²=
=-9m²+72m
m= -4
-9•(-4)²+72•(-4)=-9•16-288=-144-288=-432
2) (2х-5)²-4(х+1)(х-7)=
=4х²-20х+25-4(х²-7х+х-7)=
=4х²-20х+25-4(х²-6х-7)=
=4х²-20х+25-4х²+24х+28=
=4х+53
х=-3,5
4•(-3,5)+53=-14+53=39