Hint:

# 46 Write x^{5} as x^{4} * x, then take the product of the square roots of these for the denominator. Re-write what remains under the square root as a difference of two fractions.

# 47 Try u = (x^{2} + 1)^{1/2}. You will also need x in terms of u and an expression like h(u)du = g(x)dx for the substitution.