Integrate $e^{\sqrt{(2x+1)}}$ Integrate $e^{\sqrt{(2x+1)}}$
what I did :
let $u=2x+1$
,$du=2dx$
I plugged in those value and did the integration, is this wrong? as my answer is said to be wrong and it was solved by integration by parts instead of u-sub

That's not wrong, per se. (in the sense that the substitution is a valid one) but when you got $\int 2 e^{\sqrt{u}} du$, how did you "do the integration"? 
A better approach might be to see that the square root is a problem, and let 
$$
u^2 = 2x + 1 \\
2u du = 2dx
$$
so that you get 
$$
\int e^u u ~ du
$$
which is then amenable to integration by parts.  
