Since
du
dx
=
4x
2 = 2(2x
1),
dx
=
1
2(2x
1)
du.
You can input this as
1/(4x-2), 1/(4*x-2), 1/(2*(2x-1)) or 1/(2(2x-1))
(take your pick; spaces are optional). Don't forget to enclose the entire denomiator in parentheses.
2 = 2(2x1),
1) 2 = 2(2x1),1)