A

đặt A=\(\sqrt{a+b}\) \(\Rightarrow\) A^2=a+b

B=\(\sqrt{a}\) +\(\sqrt{b}\) \(\Rightarrow\) B^2=a+b<a+b+2\(\sqrt{ab}\)

vì a>0,b>0 =>2\(\sqrt{ab}\) >0

do vậy a+b <a+b+2\(\sqrt{ab}\)

=>A^2<B^2 =>A<B

Choose the letter A, B, C or D the word that has different stress pattern from others.

A. supermarket

B. student

C. doctor

D. present