(n-1)^2x^2-5n(n-1)x+(6n^2-n-1)=0至少有一个整数根.则所有n值的和为?

f(x)=e^x-x 求证(1/n)^n+(2/n)^n+...+(n/n)^n 若(x^2+1/x)^n(n∈N+,n x^(n)*x^(n+1)+x^(2n)*x (4x^n-2x^n-1-3x^n+2)÷（-5x^n-1) x^n-1(3x^n+4x^n+1-5x^n+2) 因式分解：(x^n+1)+(2x^n)+(x^n-1) x^n+1-2x^n+x^n-1因式分解 x^n-1-2x^n+x^n-1因式分解 分解因式x^n-x^(n-1)+x^(n-2) x^n-2x^n+1,因式分解 (-x^2n-2)*(-x)^5÷[x^n+1*x^n*(-x)]=? (-x^2n-2)(-x)^5÷[x^n+1·x^n`(-x)] 因式分解：x^(2n)+(2x)^(n)+4^(n-1) x^2n+(2x)^n+4^(n-1) 因式分解 x^n*x^n+1*(-x)^2n*x+(-x)^2n+3x^2n-2*x 约分(x^n+2)+(x^n+1)-6x^n/(2x^n+1)+5x^n-(3x^n-1) lim[n/(n*n+1*1)+n/(n*n+2*2)+...+n/(n*n+n*n)],当x趋向无穷大时,怎么求极限, 计算(x^(2n)+x^n+1)(x^(3n)-x^(2n)+1)