Question

Tim x,y,z bt

a. \(\frac{x^2}{2}+\frac{y^2}{3}+\frac{z^2}{4}=\frac{x^2+y^2+z^2}{5}\)

b. 9x²+y²+2z²-18x+4z-6y+20=0

Answer 1

ko biết

Answer 2

ko bt thi cam

Answer 3

a)       \(\frac{x^2}{2}+\frac{y^2}{3}+\frac{z^2}{4}=\frac{x^2+y^2+z^2}{5}\)

\(\Leftrightarrow\)\(\frac{x^2}{2}-\frac{x^2}{5}+\frac{y^2}{3}-\frac{y^2}{5}+\frac{z^2}{4}-\frac{z^2}{5}=0\)

\(\Leftrightarrow\)\(\frac{3}{10}x^2+\frac{2}{15}y^2+\frac{1}{20}z^2=0\)

\(\Leftrightarrow\)\(x^2=y^2=z^2=0\)

\(\Leftrightarrow\)\(x=y=z=0\)

Answer 4

giải phương trình 9x²+y²+2z²-18x+4z-6y=20=0