kaitokid sao lại là natsu

ta có: x:y:z=3:4:5\(\Rightarrow\frac{x}{3}=\frac{y}{4}=\frac{z}{5}=k\Rightarrow x=3k;y=4k;z=5k\)

\(2\left(3k\right)^2+2\left(4k\right)^2-3\left(5k\right)^2=-100\)

\(18k^2+32k^2-75k^2=-100\)

\(-25k^2=-100\)

\(k^2=-100:\left(-25\right)\)

\(k^2=4\Rightarrow k=+_{_-}2\)

*vs k=-2, có:x=-2.3=-6

    y=-2.4=-8

z=-2.5=-10

*vs k=2. có:x=2.3=6

y=2.4=8

z=2.5=10