\(A=\frac{a^3+2a^2-1}{a^3+2a^2+2a+1}\)
\(=\frac{a^3+a^2+a^2-1}{a^3+a^2+a^2+a+a+1}\)
\(=\frac{a^2\left(a+1\right)+\left(a+1\right)\left(a-1\right)}{a^2\left(a+1\right)+a\left(a+1\right)+\left(a+1\right)}\)
\(=\frac{\left(a^2+a-1\right)\left(a+1\right)}{\left(a^2+a+1\right)\left(a+1\right)}\)
\(=\frac{a^2+a-1}{a^2+a+1}\)
\(A=\frac{a^3+2a^2-1}{a^3+2a^2+2a+1}=\frac{a^3+2a^2+\left(-1\right)}{a^3+2a^2+2a+1}=\frac{-1}{2a+1}\)
\(A=\frac{a^3+2a^2-1}{a^3+2a^2+2a+1}\)
\(A=\frac{\left(a+1\right)\left(a^2+a-1\right)}{\left(a+1\right)\left(a^2+a+1\right)}=\frac{a^2+a-1}{a^2+a+1}\)
$A=\frac{a^3+2a^2-1}{a^3+2a^2+2a+1}=\frac{a^3+2a^2+\left(-1\right)}{a^3+2a^2+2a+1}=\frac{-1}{2a+1}$
Rút gọn biểu thức
A=$\frac{a^3+2a^2-1}{a^3+2a^2+2a+1}$
$A=\frac{a^3+2a^2-1}{a^3+2a^2+2a+1}=\frac{a^3+2a^2+\left(-1\right)}{a^3+2a^2+2a+1}=\frac{-1}{2a+1}$