$2√32-√50+√98$  

1.       If a and b are positive integers, which of the following is/are correct?


 $I.\sqrt{a^2+b^2}=a+b$  

 $II.\sqrt{a^2b^2}=ab$  
 $III.\sqrt{2a^2b}\times\sqrt{6a^3b}=2a^2b\sqrt{3a}$