-(4x+18)/(x²-x-6)+(x+3)/(x-3)=
=-(4x+18)/((x-3)(x+2))+(x+3)/(x-3)=
=(-4x-18+x²+5x+6)/(x-3)(x+2)=
=(x²+x-12)/(x-3)(x+2)=
=(x+4)(x-3)/(x-3)(x+2)=(x+4)/(x+2)
(7x-y)(3x+2xy-4y)=21х^2+14х^2у-28ху-3ху-2ху^2+4у^2=21х^2+14х^2у-31ху-2ху^2+4у^2.
А квадрат - 4
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вложение...............................................