1. 3 (16+20ху - 20ху-25хy^2)= 3 (16-25хy^2)=48-75хy^2
2. (х^2- у^3) ^2= х^4-y^5
3. ( с+m)^2- ( с-m)^2= (c^2+2cm+m^2)- (c^2-2cm+m^2)=c^2+2cm+m^2-c^2+2cm-m^2=4cm
1. 3 (16+20ху - 20ху-25хy^2)= 3 (16-25хy^2)=48-75хy^2
2. (х^2- у^3) ^2= х^4-y^5
3. ( с+m)^2- ( с-m)^2= (c^2+2cm+m^2)- (c^2-2cm+m^2)=c^2+2cm+m^2-c^2+2cm-m^2=4cm