Integral of a base to a quadratic: .

Since we know the integral , we should try a substitution for the exponent:

Let . Then .

Hence the combination in the original problem is .

Now we substitute and use the Scalar Multiple Rule for integrals:

Now we use the integral for the exponential of a general base:

Finally, we substitute for u to get the result in terms of x:

Notice that the exponent in the resulting function is the same as that in the original problem.