1994 x 867 + 1995 x 133

= 1728798 + 265335

= 1994133 .

ai k mik , mik k lại

                                                          2870 . 2880 . 2890 . 2900 . 2910 . 2920

Ta có:

\(a+b+c\left(\frac{1}{a+b}+\frac{1}{b+c}+\frac{1}{c+a}\right)=2012.\frac{1}{503}\)

\(\Rightarrow\frac{a+b+c}{a+b}+\frac{b+c+a}{b+c}+\frac{c+a+b}{c+a}=\frac{2012}{503}\)

\(\Rightarrow\left(1+\frac{c}{a+b}\right)+\left(1+\frac{a}{b+c}\right)+\left(1+\frac{b}{c+a}\right)=4\)

\(\Rightarrow\left(1+1+1\right)+\left(\frac{a}{b+c}+\frac{b}{c+a}+\frac{c}{a+b}\right)=4\)

\(\Rightarrow3+\left(\frac{a}{b+c}+\frac{b}{c+a}+\frac{c}{a+b}\right)=4\)

\(\Rightarrow\frac{a}{b+c}+\frac{b}{c+a}+\frac{c}{a+b}=1\)