vikusya20001 А)2m^6+5m^6-8m^6-11m^6= -12m^6
б)-3,1y^2+2,1y^2-y^2= -2y^2
в)12ab-5ab-2ab= 5ab
г) 9x^2y+x^2y-13x^2y-9x^2y= -12x^2y