Câu hỏi 46
(YUG) Cho
$$f(a,b,c)=\left|\frac{|b-a|}{|ab|}+\frac{b+a}{ab}-\frac2c\right|+\frac{|b-a|}{|ab|}+\frac{b+a}{ab}+\frac2c.$$
Chứng minh rằng $f(a,b,c)=4\max\{1/a,1/b,1/c\}$.
$$f(a,b,c)=\left|\frac{|b-a|}{|ab|}+\frac{b+a}{ab}-\frac2c\right|+\frac{|b-a|}{|ab|}+\frac{b+a}{ab}+\frac2c.$$
Chứng minh rằng $f(a,b,c)=4\max\{1/a,1/b,1/c\}$.