查人人中国名人网厦大网络教育怎么样:一道数学题 急用
来源：百度文库 编辑：查人人中国名人网 时间：2024/04/29 13:43:32
化简后求值：（3a-1）(3a-2)-3(2-5a+3a^2),其中a=-1/3.
（3a-1）(3a-2)-3(2-5a+3a^2)
=（3a-1）(3a-2)-3(3a-2)(a-1)
=(3a-2)[3a-1-3(a-1)]
=2(3a-2)
=2*(-1-2)
=-6
=9a^2-9a+2-6+15a-9a^2
=6a-4
当a=-1/3
=-6
=3a^2-9a+2-6+15a-9a^2
=-6a^2+6a-4
当a=-1/3
=-2/3-2-4
=-6 2/3
=(3a-1)*(3a-2)-3(a-1)(3a-2)
=(3a-2)[3a-1-3(a-1)]
=(3a-2)(3a-1-3a+3)
=(3a-2)2
当A=-1/3时
原式＝（-1/3*3-2）*2
＝-6
（3a-1）(3a-2)-3(2-5a+3a^2)
=（3a-1）*(3a-2)-3*(3a-2)*(a-1)
=2(3a-2) =-6
（3a-1）(3a-2)-3(2-5a+3a^2)
=（3a-1）(3a-2)-3(3a-2)(a-1)
=(3a-2)[3a-1-3(a-1)]
=2(3a-2)
=2*(-1-2)
=-6