Question

tim nghiem nguyen duong: \(3^x=y^2+2y\)

Answer 1

\(\Leftrightarrow3^x=y\left(y+2\right)\)

\(\Rightarrow\left\{{}\begin{matrix}y=3^a\\y+2=3^b\end{matrix}\right.\) với \(b>a\) và \(a+b=x\)

\(\Rightarrow3^b-3^a=2\Rightarrow3^a\left(3^{b-a}-1\right)=2\)

Nếu \(a>0\Rightarrow3^a\left(3^{b-a}-1\right)>3>2\) (ktm)

\(\Rightarrow a=0\Rightarrow b=1\)

\(\Rightarrow\left\{{}\begin{matrix}y=1\\x=1\end{matrix}\right.\)