Question

rút gọn

\(A=\dfrac{x^7+x^6+x^5+x^4+x^3+x^2+x+1}{x^2-1}\)

Answer 1

\(=\dfrac{x^6\left(x+1\right)+x^4\left(x+1\right)+x^2\left(x+1\right)+1.\left(x+1\right)}{\left(x+1\right)\left(x-1\right)}=\dfrac{\left(x+1\right)\left(x^6+x^4+x^2+1\right)}{\left(x-1\right)\left(x+1\right)}=\dfrac{x^6+x^4+x^2+1}{x+1}\)