simplify the expression:

6x(2x+1)^1/2+3x^2(2x+1)^-1/2

I see a common factor of 3x(2x+1)^(-1/2)

so we have
3x(2x+1)^(-1/2)[2(2x+1) + x]
= 3x(2x+1)^(-1/2)(5x+2)