求方程2/n+3/n+1+4/n+2=133/60

方程2分之n(n-3)=20 求n 解一个方程,950n+(1/2)n(n-1)乘(-100)=5000求n 求极限 lim(n->无穷)[(3n^2-2)/(3n^2+4)]^[n(n+1)] 求lim(n+1)(n+2)(n+3)/(n^4+n^2+1) 若n²+3n=1,求n(n+1)(n+2)+1的值. 16n^a+4n^3+6n^2+7^n=0,求n 已知方程(2-n)x^|n|-1=4是关于x的一元一次方程,求代数式(n+3)^2011 若n为正整数,求1/n(n+1)+1/(n+1)(n+2)＋1/(n+2)(n+3)+1/(n+3)(n+4)+.+1/ 求极限Xn=n/(n^2+1)+n/(n^2+2)+n/(n^2+3)+……+n/(n^2+n), 1\n(n+3)+1\(n+3)(n+6)+1\(n+6)(n+9)=1\2 n+18 n为正整数,求n的值 证明不等式：(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n 证明：1+2C(n,1)+4C(n,2)+...+2^nC(n,n)=3^n .(n∈N+)