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1) (3х-1)(3х+1)+(3х+1)²=(3х+1)(3х-1+3х+1)=6х·(3х+1) 2)25а-ав²=а(25-в²)=а(5-а)(5+а) 3)х³-ху²-6у²+6х²=х(х²-у²)-6(у²-х²)=х(х²-у²)+6(х²-у²)=(х²-у²)(х+6)=(х-у)(х+у)(х+6)