65（a^4-1)过程？？[（3a+2)(3a-2)]^2-[(2a+3)(2a-3)]^2=(9a^2-4)^2-(4a^2-9)^2=(13a^2-13)(5a^2+5)=65(a^2-1)(a^2+1)=65(a^4-1)