I got it !!
it will = sec^-1 [ln t + 1] + C
Solving by :
Sqrt( u . (u+2) )
= sqrt [ (u+0) . (u+1+1) ]
= sqrt [ (u+1-1) . (u+1+1) ]
then i will mulitplyed the brackets
it will be = sqrt [ (u+1)^2 - 1 ]
put k = u+1
dk = du
it will be k . Sqrt(k^2 -1)
Trigonometric substitution k = sec θ
One question : it allowed to multiply the brackets in BLUE making u+1 as an one thing??
i hope u will understand what i mean !
Again: Sorry for bad english