Question

\(\frac{a}{3}=\frac{b}{4};\frac{b}{2}=\frac{c}{5}\)và a+b+c=3

Answer 1

do b/2=c/5nên b/2x1/2=c/5x1/2

=>b/4=c/10=>a/3=b/4=c/10

=(a+b+c)/(3+4+10)=3/17

=>a=3/17x3=..,b=...,c=...

Answer 2

Ta có: \(\frac{a}{3}=\frac{b}{4};\frac{b}{2}=\frac{c}{5}\Rightarrow\frac{a}{6}=\frac{b}{12}=\frac{c}{20}=\frac{a+b+c}{6+12+20}=\frac{3}{38}\)

=> \(a=\frac{3}{38}.3=\frac{9}{19}\)

      \(b=\frac{3}{38}.12=\frac{18}{19}\)

       \(c=\frac{3}{38}.20=\frac{30}{19}\)

Vậy a = 9/19 ; b = 18/19 ; c = 30/19

Answer 3

Từ a/3 = b/4 => a/6 = b/8

     b/2 = c/5 => b/8 = c/20

=> a/6 = b/8 = c/20 =k

=> a = 6k, b = 8k, c = 20k

Mà: a + b + c = 3

=> 6k + 8k + 20k = 3

=> 34k = 3

=> k = 3/34

Vậy a = 3/34 x 6 = ...

       b = 3/34 x 8 = ...

       c = 3/34 x 20 = ...