Question

giải hệ phương trình sau : U1*q^3 + U1*q = 60 U1*q^4 + U1*q^2 = 180

Answer 1

\(\Leftrightarrow\left\{{}\begin{matrix}u1\cdot q\left(q^2+1\right)=60\\u1\cdot q^2\left(q^2+1\right)=180\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\dfrac{1}{q}=\dfrac{1}{3}\\u1\cdot q\cdot\left(q^2+1\right)=60\end{matrix}\right.\)

=>\(\left\{{}\begin{matrix}q=3\\u1\cdot3\cdot\left(3^2+1\right)=60\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}q=3\\u1=2\end{matrix}\right.\)