Question is:

y = (x + 1) \sqrt[x - 1]

So I convert to

y = (x + 1) (x - 1)^(1/2)

Then

dy/dx = (x -1)^(1/2) . 1 + (x + 1) 1/2(x - 1)^(-1/2) . 1

y= (x - 1)^{1/2} + \frac{(x + 1}{2(x - 1)^{\frac{1}{2}}}

Is this correct?

Book says numerator is 3x - 1!

What have I done wrong?

Angus