Let's first consider the differential of 2x. We know that this becomes ln(2)*2x. We can compare this to the integrand and see that this is very close indeed! The only problem is that ln(2). So now consider 2x / ln(2). When we differentiate this we get 2x. So we conclude that the integral of 2x is 2x / ln(2) + C (don't for get the +C!). This is sometimes known as the reverse chain rule.