Question

\(\dfrac{2a}{3}=\dfrac{3b}{4}=\dfrac{4c}{5}va\alpha+b+c=49\)

Answer 1

Ta có 

Answer 2

lộn

 

Answer 3

Ta có \(\dfrac{2a}{3}=\dfrac{3b}{4}=\dfrac{4c}{5}hay\dfrac{a}{\dfrac{3}{2}}=\dfrac{b}{\dfrac{4}{3}}=\dfrac{c}{\dfrac{5}{4}}\)

Áp dụng tính chất dãy tỉ số bằng nhau ta có 

 \(\dfrac{a}{\dfrac{3}{2}}=\dfrac{b}{\dfrac{4}{3}}=\dfrac{c}{\dfrac{5}{4}}=\dfrac{a+b+c}{\dfrac{3}{2}+\dfrac{4}{3}+\dfrac{5}{4}}=\dfrac{49}{\dfrac{49}{12}}=12\)

vậy \(a=12.\dfrac{3}{2}=18\)

\(b=12.\dfrac{4}{3}=16\)

\(c=12.\dfrac{5}{4}=15\)

vậy a=18 ;b=16 ;c=15