8x=-16
x=-16:8
x=-2
абсцисса -2
1) х-3у+х²-9у²=(х-3у)+(х²-9у²)=
=(х-3у)+(х²-(3у)²)=(х-3у)+(х-3у)(х+3у)=
=(х-3у)(1+х+3у)
2) 1-х²+10ху-25у²=1-(х²-10ху-25у²)=
=1-(х-у)²=(1+х-у)(1-х+у)
3) (х+5)³-64=(х+5)³-4³=
=(х+5-4)((х+5)²+(х+5)•4+4²)=
=(х+1)(х²+10х+25+4х+20+16)=
=(х+1)(х²+14х+61)
A³-b³=? a-b=7 ab=-6
a³-b³=(a-b)(a²+ab+b²)=7*(a²+ab-3ab+3ab+b²)=7*(a²-2ab+b²+3ab)=
=7*((a-b)²+3ab)=7*(7²+3*(-6))=7*(49-18)=7*31=217.
Ответ: a³-b³=217.