What happens if we try the substitution y = x² − 4? The transformation formula for differentials is dy = 2x⋅dx and the expression on the right is not in the integral, which does not sound too optimistic. When we try to rearrange the differential transformation formula, we get this.

Our suspision is vindicated, the new integral is not any better than the given one.

Now we will try out our favorite mixed substitution for removing roots, that is, y² = x² − 4. Differentials get transformed using the formula 2y⋅dy = 2x⋅dx and again we have to tweak it a bit.

Again, this was not any help.