х²+3х+2ху+6у=(х²+3х)+(2ху+6у)=x·(x+3)+2y·(x+3)=(x+3)·(x+2y)
или
х²+3х+2ху+6у=(х²+2ху)+(3х+6y)=)=x·(x+2y)+3·(x+2y)=(x+2y)·(x+3)
2,5у(4у-2)-5у(2у-8)=5у(2у-1)-5у(2у-8)=5у(2у-1-2у-8)=5у(-9)=-45у
А) x²+4x=(x²+4x+4)-4=(x+2)²-4
б) x²-6x=(x²-6x+9)-9=(x-3)²-9
в) x²+7x=(x²+6x+9)+x-9=(x+3)²+x-9
<span>г) x</span>²<span>-x=(x</span>²-2x+1)+x-1=(x-1)²+x-1