化简:5(y-2)^2-3(y+1)(y-1);(3a+2b)(2b-3a)(9a^2-4b^2)
问题描述：
化简:5(y-2)^2-3(y+1)(y-1);(3a+2b)(2b-3a)(9a^2-4b^2)
过程仔细一点
答
1.5(y-2)^2-3(y+1)(y-1)
=5(y^2-4y+4)-3(y^2-1)
=5y^2-20y+20-3y^2+1
=2y^2-20y+21
2.(3a+2b)(2b-3a)(9a^2-4b^2)
=-(3a+2b)(3a-2b)(9a^2-4b^2)
=-(9a^2-4b^2)(9a^2-4b^2)
=-(9a^2-4b^2)^2