Question

tìm 2 số thực x,y biết x/2=y/5 và x+y=42

Answer 1

áp dụng t/c dtsbn ta có:

\(\dfrac{x}{2}=\dfrac{y}{5}=\dfrac{x+y}{2+5}=\dfrac{42}{7}=6\)

\(\dfrac{x}{2}=6\Rightarrow x=12\\ \dfrac{y}{5}=6\Rightarrow y=30\)

Answer 2

\(\dfrac{x}{2}=\dfrac{y}{5}=\dfrac{x+y}{2+5}=\dfrac{42}{7}=6\)

\(\Rightarrow\left\{{}\begin{matrix}x=2.6=12\\y=5.6=30\end{matrix}\right.\)