Question

tìm x,y,z biết

xy=\(\dfrac{1}{2}\) ;yz=\(\dfrac{3}{5}\) ;xz= \(\dfrac{27}{10}\)

Answer 1

ta có:x.y.y.z.x.z=\(\dfrac{1}{2}.\dfrac{3}{5}.\dfrac{27}{10}=\dfrac{81}{100}\)

=>(x.y.z)²= \(\left(\dfrac{9}{10}\right)^2=\left(\dfrac{-9}{10}\right)^2\)

Nếu x.y.z=\(\dfrac{9}{10}\)

=>\(\left\{{}\begin{matrix}x=\dfrac{3}{2}\\y=\dfrac{1}{3}\\z=\dfrac{9}{5}\end{matrix}\right.\)

Nếu x.y.z=\(\dfrac{-9}{10}\)

=>\(\left\{{}\begin{matrix}x=\dfrac{-3}{2}\\y=\dfrac{-1}{3}\\z=\dfrac{-9}{5}\end{matrix}\right.\)