①证明当μ。≠ μ,且电子浓度=(n)_(i)sqrt ({u)_(p)/(u)_(n)}, =(n)_(1)sqrt ({mu )_(n)/(mu )_(p)}时材料的电导率最小，并求σmin的表达式②试求300K时Ge和Si样品的最小电导率的数值，并和本征电导率相比较。

①证明当μ。≠ μ,且电子浓度eta =(n)_(1)sqrt ({mu )_(p)(mu )_(n)} =(n)_(1)sqrt ({mu )_(n)/(H)

(B) dfrac (sqrt {n)(overline (X)-mu )}(S)sim t(n-1).-|||-(C) dfrac (sqrt {n)(ove

求极限lim_(ntoinfty)((n)/(1^2)+sqrt(1)+n^(2)+(n)/(2^2)+sqrt(2)+n^(2)+...+(n)/(n^2)+

A approx N(mu ,1).Bapprox N(mu ,1).C approx N(mu ,1).D approx N(mu ,1).设总体其中未知，如

12.证明lim_(ntoinfty)((1)/(sqrt(n^2)+1)+(1)/(sqrt(n^2)+2)+...+(1)/(sqrt(n^2)+n))=1

设 _(1)=10, _(n+1)=sqrt (6+{a)_(n)} 证明:极限liman存在,并求之.

【例】求极限lim_(ntoinfty)((1)/(n+1)+(1)/(n+sqrt(2))+...+(1)/(n+sqrt(n)))。【例】求极限$\lim_

(D) (overline (x)-(u)_(a12)dfrac (2)(sqrt {n)},overline (x)+(u)_(a12)dfrac (2)(s

A)(overline(X) - u_(alpha) (2)/(sqrt(n)), overline(X) + u_(alpha) (2)/(sqrt(n))

2.lim_(n to infty)(sqrt(n+1)-sqrt(n))sqrt(n+1)=_____.2.$\lim_{n \to \infty}(\sqr