x/x²-x+1=7
(x/x^2-x+1)^2=7^2
x^2/(x^2+1-x)^2=49
x^2/((x^2+1)^2-x^2)=49
x^2/(x^4+2x^2+1-x^2)=49
x^2/x^4+x^2+1=49
所以x²/x四次方+x²+1=49x^2/(x^4++1-x^2)=49这里的2x^2是2X么还是2乘是2X哦！明白了！