3（2a+1)(2a-1)-4(3a-2)(3a+5)=3(4a²-1)-4(9a²+9a-15)=12a²-3-36a²-36a+60=-24a²-36a+57
=3*（4a^2-1）-4*(9a^2+9a-10)=-24a^2-9a+37
