1.
А+В=а^2+аб-4б^2-2а^2-2аб+б^2=
=-а^2-аб-3б^2
А-В=а^2+аб-4б^2+2а^2+2аб-б^2=
=3а^2+3аб-5б^2
2.
а)=-6аб+3б^2
б)=4х^4+12х^3у-4х^2у^2
3.
=а^2+2аб-бх^2-х^3+ах^2-б^2-бх^2+х^3=а^2+2аб+ах^2-б^2=
=(а^2+2аб+б^2)+ах^2=
=(а+б)^2 +ах^2
6.
а)=15а-6б-15а+20б=14б=
=14×(-2)=-28
б)=12а^3-4а^2б^2-4аб^3-12а^3 -6а^2б^2+4аб^3=-10а^2б^2=
=-10×(-12/17)^2×(1 5/12)^2=
=-10
7.
=х-(2+х-1)+х-5-2х=
=х-х-1-5-х=-х-6
-х-6=0
-х=6
х=-6