Question

Tìm A biết rằng :

\(A=\frac{a}{b+c}=\frac{b}{a+c}=\frac{c}{a+b}\). 

Tìm A = ?

Answer 1

Theo t/ c dãy tỉ số= nhau:

 a/b+c=b/a+c=c/a+b=a+b+c/(a+a)+(b+b)+(c+c)=a+b+c/2a+2b+2c=a+b+c/2.(a+b+c)=1/2

 Vậy A=1/2

Answer 2

\(\frac{a}{b+c}=\frac{b}{a+c}=\frac{c}{a+b}=\frac{a+b+c}{2\left(a+b+c\right)}=\frac{1}{2}\)

\(\Rightarrow A=\frac{1}{2}\)