câu a ghi đề lại cho anh đc ko ko thấy gì hết
a, Ta có: \(\left(x-\dfrac{3}{5}\right)^{2004}\ge0\forall x\in Q\)
\(\left(y+2,9\right)^{2006}\ge0\forall x\in Q\)'
\(\Rightarrow\left(x-\dfrac{3}{5}\right)^{2004}+\left(y+2,9\right)^{2006}\ge0\)
Dấu "=" xảy a khi: \(\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{3}{5}=0\\y+2,9=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{5}\\y=-2,9\end{matrix}\right.\)
b, Nhân 3 vế lại ta có:
\(\left(xyz\right)^2=\dfrac{4}{25}\Rightarrow xyz=\dfrac{2}{5}\)
\(\Rightarrow\left\{{}\begin{matrix}x=xyz:yz=0,3\\y=xyz:xz=\dfrac{-20}{7}\\z=xyz:xy=\dfrac{-7}{15}\end{matrix}\right.\)
c, \(2^x-2^9=496\)
\(2^x=496-2^9=-16=-2^4\)
cái này anh cx ko bt :D
