1.若x分之(x+1)=5,求（x的四次方-x的平方+1）分之（x的四次方+x的平方+1）的值.（详见内

1.(x+1//x=5
∴1/x=4
∴x=1/4
(x^4+x^2+1)/(x^4-x^2+1)=(x^2+1/2)^2/(x^2-1/2)^2=[(x^2+1/2)/(x^2-1/2)]^2=[(1/16+1/2)/(1/16-1/2)]^2=(-9/7)^2=81/49
2.1/[x(x+1)]+2/[(x+1)(x+3)]+3/[(x+3)(x+6)]=[1/x-1/(x+1)]+[1/(x+1)-1/(x+3)]+[1/(x+3)-1/(x+6)]=1/x-1/(x+6)