(13X-X2/X+1 )(X+13-X/X+1)=42 求X的值(要详细的解体步骤)越好 thanks

(x2+4x)/(x-1) x2-x 不等式(x2-2x-3)(x2-13x+42) 因式分解x2+13x+30 6x2-13x+6 解方程1/x2+2x+10+1/x2+11x+10+1/x2-13x+10=0 化简x/x2+x除以x2+x-2/x2-1+x+1/x+2 2x²-7x-1518x²-19x+56x2-13x+6-1+y+20y² 填九宫格帮帮忙.x x 6 x x 7 x x 98 x x x 3 x 1 x x 9 x x 6 x 5 x 3 x x x 3 x x x x 1 8x x x 9 x 1 x x x2 1 x x x x 6 x x x 6 x 7 x 3 x x 1 x x 9 x 2 x x x 47 x x 8 x x 5 x x 13-4x2≥0 x2-6x+4≥0 （x-1）（2-x）≥0 x（1-x）>x（2x-3）+1 -6x2-x+1≤0 函数f(x)=3x/x2+x+1 (x 函数f(x)=3x/x2+x+1 (x X2-13X+1=0 那么X2+1/ X2的值是多少?X2是X的平方 7/x2+x+1/x2-x=6/x2-1 MATLAb编程解方程clear;clcsyms xfor n=1:6X2=solve('(x-1)*(x-2)*(x-3)*(x-4)*(x-5)*(x-6)*(x-7)*(x-8)*(x-9)*(x-10)*(x-11)*(x-12)*(x-13)*(x-14)*(x-15)*(x-16)*(x-17)*(x-18)*(x-19)*(x-20)+1e-n*x^19=0',x);double(X2)end与直接代入n=1,2,...6算出来 函数y=4x2+8x+13/6(x+1) (x>-1)的值域是 3/x2 -3x+2-1/x-2=1/x2 -x+4/x2 -2x 通分 3x/x2-2x,2x+1/4-x2,3/2x2+4x