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计算:12+23?1?(3+1)

原式=23+2(3+1)(3+1)(3?1)-1=23+3+1-1=33.

(1)原式=(18+0.375)+(-0.75-214)=0.5+(-3)=-2.5;(2)原式=-14×12×(-3535)×4=35310;(3)原式=-25+12+16-18=-15;(4)原式=-1-1+6÷2=-1-1+3=1.

(1)12-7+18-15=30-22=8;(2)(1?23)÷(?116)+(?2)2×(?3)=13÷(-116)+4×(-3)=-27-12=-1227.

3/4-1/4+11/23+12/23=2/4+23/23=1/2+1=1.5

(1)(-16+34-512)×(-12),=(-16)×(-12)+34×(-12)+(-512)×(-12),=2+(-9)+5,=-2.(2)原式=-1-[-3×49-83÷(-8)],=-1-[-43-83×(-18)],=-1-[-43+13],=-1-(-1),=0.

(1)解:根据题意得:n=(n+1)?n?1n+1n;(2)证明:∵(n+1)?n?1n+1n=(n+1)(n?1)n+1n=n2?1+1n=n,∴n=(n+1)?n?1n+1n.故答案为:(n+1)?n?1n+1n

47

1^3=1,2^3=8,3^3=27,4^3=64,……照此类推,第n个数是n^3.

12.1÷(3+23)=12.1÷323=3.3答:这个数是3.3.

(1)2014×101.1-201.3×1011=(2014-2013)×101.1=1×101.1=101.1;(2)(13-14)÷12+56=112÷12+56=16+56=1;(3)23×3÷23×3=2÷23×3=3×3=9;(4)89×[34-(716-0.25)]=89×[34-316]=89×916=12.

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