(2+3а)(5-а) - (2-3а ) (5+а) при а = -1.5

(2+3а)(5-а)-(2-3а)(5+а)=10-2а+15а-3а²-(10+2а-15а-3а²)= =10+17а-3а²-10-2а+15а+3а²=30а=30*(-1,5)=-45