今天刚考完~M51，说下数学。。

orchidsul

楼主运气很好，我只见到三四个狗

-- by 会员 oh9527 (2011/1/18 16:33:03)

人品守恒。。我的verbal死的很惨

-- by 会员 lijm139 (2011/1/19 0:34:37)

同意，我的数学也很好，verbal完全没有pace，10题之后开始赶时间，整个慌乱。我的verbal再差也差不到最后那个成绩。也许不应该赶时间，平静的做，能做多少做多少。

cherry12345

Thanks so much for your help, SCDAR!!

S=1+1/a+1/a2+1/a3; T=1+S/a. 问T-S=？

S/a = 1/a +1/a2+1/a3+1/a4

T-S= 1+S/a -S=1+(1/a +1/a2+1/a3+1/a4) - (1+1/a+1/a2+1/a3) = 1/a4

I wonder, is that S/a should mutibly "a" in the equation of "S"? which is S/a = 1/a+1/a^3+1/a^4+1/a^5 ? I am so confused in this part.  looking forward for your advise.

xuyuej

T-S=1+S(1-a)/a
S=1+1/a+1/a^2+1/a^3 can be written as 1+(a^2+a^1+a)/a^3

then the T-S can be as follows

=1+(a^3+a^2+a+1)(1-a)/a^4
=1+{[a^2(a+1)+(a+1)](1-a)}/a^4
=[a^4-(a^2+1)(a^2-1)]/a^4
=(a^4-a^4+1)/a^4
=1/a^4

cherry12345

Thanks very much, suyuej, I get it now.  Wish you have a good scroe in G.

dingyanan1986

LZ和我情况一样，今天杯具二战M51，几乎全是狗，V20................人品守恒啊T,T