A Level Maths Question

[river gorge]

How does it go from step 2 to 3

[river field]

$$\sqrt{x} = \frac{u+1}{8}$$ \ $$ \frac{\sqrt{x}du}{4} = dx$$ \ $$\int \frac1{u} \times \frac{\sqrt{x}}{4} du = \int \frac1{u} \times \frac{\frac{u+1}{8}}{4} du$$

[plush lance]

Xotiic