Solving Improper Integral: $\int_{-\infty}^{0} 2^{r}dr$

[iRaid]

Homework Statement

$$\int_{-\infty}^{0} 2^{r}dr$$

Homework Equations

The Attempt at a Solution

$$\int_{-\infty}^{0} 2^{r}dr = \lim_{t \to -\infty} \int_t^0 2^{r}dr=\lim_{t \to -\infty} \frac{2^{r}}{ln2}|_{t}^{0} = \lim_{t \to -\infty} \frac{1}{ln2}-\frac{2^{t}}{ln2}$$

Which I thought = ∞, but I guess not. It's supposed to be 1.4427 according to wolfram..

 

[iRaid]

I think I found my error...
$$\lim_{t \to -\infty} \frac{1}{ln2}-\frac{2^{t}}{ln2}=\lim_{t \to -\infty} \frac{1}{ln2}-\frac{1}{(ln2)(2^{t})}$$

So then the 1/(ln2)(2^t) becomes 1/0 and then 1/ln2 = what wolfram gets..