№659
а)= х-у+у-х-х-у=-х-у
-х-у=-(-5)-3,2=5-3,2=1,8
б) =m+n-n-p-m-p=-2p
-2p=-2*4=-8
№658
а)=6а²-3а+1+6а²-1=12а²-3а
=6а²-3а+1-6а²+1=-3а+2
б)=n³+2n²-n+1+1-n³=2n²-n+2
=n³+2n²-n+1-1+n³=2n³+2n²-n
в)=к³-3к²+1+2к³-3к²+4=3к³-6к²+5
=к³-3к²+1-2к³+3к²-4=-к³-3
г)=3х²-2х+7+2х²+2х+7=5х²+14
=3х²-2х+7-2х²-2х-7=х²-4х