Question

Answer 1

Bài 3:

1) Xét ΔABC có MN//BC

⇒ \(\dfrac{AM}{AB}=\dfrac{AN}{AC}=\dfrac{MN}{BC}\)

⇔ \(\dfrac{AM}{AM+MB}=\dfrac{AN}{AC}=\dfrac{MN}{BC}\)

⇔ \(\dfrac{3}{3+1,5}=\dfrac{6}{AC}=\dfrac{MN}{9}\)

⇔ \(\dfrac{2}{3}=\dfrac{6}{AC}=\dfrac{MN}{9}\)

⇒ \(\left\{{}\begin{matrix}AC=9\\MN=6\end{matrix}\right.\)

Khi \(AC=9\) ⇒ \(NC=AC-AN\)

⇔ \(NC=9-6\)

⇔ \(x=3\)

\(Vậy\left\{{}\begin{matrix}x=3\\y=6\end{matrix}\right.\)