七(下)一道数学题

ecnr 2016-6-28 374

最新回复 (2)
  • ovtwo -990471874秒前
    引用 2
    1. (2+1)(2^2+1)(2^4+1)(2^8+1)...(2^64+1) =1 *(2+1)(2^2+1)(2^4+1)(2^8+1)...(2^64+1) =(2-1)*(2+1)(2^2+1)(2^4+1)(2^8+1)...(2^64+1) =... =(2^64-1)(2^64+1) =2^128-1 2.(1+1/2)(1+1/2^2)(1+1/2^4)(1+1/2^8) =[(1-1/2)(1+1/2)(1+1/2^2)(1+1/2^4)(1+1/2^8)]/[1/2] =... =[(1-1/2^8)(1+1/2^8)]/[1/2] =[1-1/2^16]/[1/2] =2[1-1/2^16] =2-1/2^15
  • zofhs -990558223秒前
    引用 3
    (1)求(2+1)(2^2+1)(2^4+1)(2^8+1)...(2^64+1)的值; 因为2+1=2^2-1=3,所以: (2+1)(2^2+1)(2^4+1)(2^8+1)...(2^64+1) =(2^2-1)*(2^2+1)*(2^4+1).....(2^64+1) =(2^4-1)*(2^4+1)....(2^64+1) =.... =2^(64*2)-1 =2^128-1 (2)求(1+1/2)(1+1/2^2)(1+1/2^4)(1+1/2^8)的值 因为:1+1/2=3/2=3*(1/2)=3*(1-1/2),所以: (1+1/2)(1+1/2^2)(1+1/2^4)(1+1/2^8) =3*(1-1/2)*(1+1/2)*(1+1/2^2)*(1+1/2^4)*(1+1/2^8) =3*(1-1/2^2)*(1+1/2^2)*(1+1/2^4)*(1+1/2^8) =3*(1-1/2^4)*(1+1/2^4)*(1+1/2^8) =... =3*(1-1/2^16)
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