sửa đề:1+c/b chứ ko phải là a+c/b nhé bn
+)Xét a+b+c=0
=>a+b=-c;b+c=-a;c+a=-b
Khi đó \(\left(1+\frac{b}{a}\right)\left(1+\frac{a}{c}\right)\left(1+\frac{c}{b}\right)=\left(\frac{a+b}{a}\right)\left(\frac{c+a}{c}\right)\left(\frac{b+c}{b}\right)\)
\(=\frac{-c}{a}.\frac{-b}{c}.\frac{-a}{b}=-1\)
+)Xét a+b+c \(\ne\) 0
Theo t/c dãy....:
\(\frac{a+b-c}{c}=\frac{b+c-a}{a}=\frac{a+c-b}{b}=\frac{a+b-c+b+c-a+a+c-b}{c+a+b}=\frac{a+b+c}{c+a+b}=1\)
=>a+b-c=c=>a+b=2c
b+c-a=a=>b+c=2a
a+c-b=b=>a+c=2b
\(\left(1+\frac{b}{a}\right)\left(1+\frac{a}{c}\right)\left(1+\frac{c}{b}\right)=\frac{a+b}{a}.\frac{c+a}{c}.\frac{b+c}{b}=\frac{2c}{a}.\frac{2b}{c}.\frac{2a}{b}=\frac{2a.2b.2c}{a.b.c}=2.2.2=8\)
Vậy........................