\(\dfrac{a}{5}=\dfrac{b}{4}=\dfrac{c}{7}\) và \(a+2b+c=10\)
\(\Rightarrow\dfrac{a}{5}=\dfrac{2b}{8}=\dfrac{c}{7}\)
Áp dụng tính chất của dãy tỉ số bằng nhau:
\(\Rightarrow\dfrac{a}{5}=\dfrac{2b}{8}=\dfrac{c}{7}=\dfrac{a+2b+c}{5+8+7}=\dfrac{10}{20}=\dfrac{1}{2}\)
\(\dfrac{a}{5}=\dfrac{1}{2}\Rightarrow a=\dfrac{5}{2}\)
\(\dfrac{b}{4}=\dfrac{1}{2}\Rightarrow b=2\)
\(\dfrac{c}{7}=\dfrac{1}{2}\Rightarrow c=\dfrac{7}{2}\)
Từ \(\dfrac{a}{5}=\dfrac{b}{4}=\dfrac{c}{7}\)
\(\Rightarrow\dfrac{a}{5}=\dfrac{2b}{8}=\dfrac{c}{7}\)
Áp dụng tính chất của dãy tỉ số bằng nhau :
\(\dfrac{a}{5}=\dfrac{b}{4}=\dfrac{c}{7}=\dfrac{a+2b+c}{5+4+7}=\dfrac{10}{20}=\dfrac{1}{2}\)
\(+)\)\(\dfrac{a}{5}=\dfrac{1}{2}\Rightarrow x=\dfrac{1}{2}\times5=\dfrac{5}{2}\)
\(+)\)\(\dfrac{b}{4}=\dfrac{1}{2}\Rightarrow b=\dfrac{1}{2}\times4=2\)
\(+)\)\(\dfrac{c}{7}=\dfrac{1}{2}\Rightarrow c=\dfrac{1}{2}\times7=\dfrac{7}{2}\)
