could someone help me integrate the following equations because i keep getting the wrong answer and i dont no why T.T thankyou !

a) x/[(2x-1)^1/2]

b) dt/dx = 1/{2[(4-x)^2]} and that x = 0 when t=0 find x in terms of t

btw i am using the u substitution method for these two questions

thankyou so much for any help given !! =)