Cho ba so a , b ,c \(\in\) Q khac nhau tung doi mot va khac 0 thoa \(\frac{a}{b+c}=\frac{b}{a+c}=\frac{c}{a+b}\). Chung minh \(\frac{b+c}{a}=\frac{a+c}{b}=\frac{a+b}{c}\)khong phu thuoc vao gia tri cua a,b,c.
M.n oi, giup mik voi ngay mai mik phai nop roi....