Cho bốn số \(a,b,c,d\). Biết rằng \(a:b=2:3,b:c=4:5,c:d=6:7\). Ta tìm được \(a:b:c:d\) là
\(8:12:15:13\).\(16:24:32:35\).\(4:12:6:7\).\(16:24:30:35\).Hướng dẫn giải:Ta có: \(\left\{{}\begin{matrix}\dfrac{a}{2}=\dfrac{b}{3}\\\dfrac{b}{4}=\dfrac{c}{5}\\\dfrac{c}{6}=\dfrac{d}{7}\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}\dfrac{a}{16}=\dfrac{b}{24}\\\dfrac{b}{24}=\dfrac{c}{30}\\\dfrac{c}{30}=\dfrac{d}{35}\end{matrix}\right.\Rightarrow\dfrac{a}{16}=\dfrac{b}{24}=\dfrac{c}{30}=\dfrac{d}{35}\)
\(\Rightarrow a:b:c:d=16:24:30:35\).
