Tính các tổng sau:
a,A=\(\frac{x^4-\left(x-1\right)^2}{\left(x^2+1\right)^2-x^2}+\frac{x^2-\left(x^2-1\right)^2}{x^2\cdot\left(x+1\right)^2-1}+\frac{x^2\cdot\left(x-1\right)^2-1}{x^4-\left(x+1\right)^2}\)
b,B=\(\frac{x}{xy+x+1}+\frac{y}{yz+y+1}+\frac{z}{xz+z+1}\)
Giúp mình với!