北师大版七年级上册数学书习题2.14答案
1习题2.14第1题答案
(1)-34
=-(3×3×3×3)
=-81
(2)-(-3)3
=-[(-3)×(-3)×(-3)]
=27
(3)-(-2/3)4
=-(2/3×2/3×2/3×2/3)
=- 16/81
(4)(4/5)2
=4/5×4/5
=16/25
(5)-3/22
=-3/(2×2)
=-3/4
(6)-(-2/5)3
=-[(-2/5)×(-2/5)×(-2/5)]
=8/125
2习题2.14第2题答案
(1/2)7=1/128(m)
因此第7次后剩下的木棒有1/128m长
3习题2.14第3题答案
(1)1/2×1/2×1/2×1/2×1/2×1/2=[(1/2)]6=1/64
(2)1/2+1/4+1/8+…+1/26 =1-1/64=63/64