问题补充:
十二分之一等于几分之一加几分之一加几分之一 加几分之一
答案:
1/12=1/24+1/24
=1/24+1/48+1/48
=1/24+1/48+3/144
=1/24+1/48+2/144+1/144
=1/24+1/48+1/72+1/144
======以下答案可供参考======
供参考答案1:
(x-2)²-2(x+3)(x-2),
=(x²-4x+4)-2(x²+x-6)
=x²-4x+4-2x²-2x+12
=-x²-6x+16
=-9-18+16
=-11 (1)4x²-64
=4(x²-16)
=4(x+4)(x-4)
(2)4ab²-4a²b-b³
=-b(4a²-4ab+b²)
=-b(2a-b)²