Các bn giúp mk vd 5 vs ạ mk cảm ơn!!!
View attachment 96625
[tex]P=\frac{2005a}{ab+2005a+2005}+\frac{b}{bc+b+2005}+\frac{c}{ac+c+1}\\\\ =\frac{2005a}{ab+2005a+2005}+\frac{ab}{abc+ab+2005a}+\frac{abc}{a^2bc+abc+ab}\\\\ =\frac{2005a}{ab+2005a+2005}+\frac{ab}{ab+2005a+2005}+\frac{2005}{ab+2005a+2005}\\\\ =1[/tex]