# Thread: power series representation of a function

1. ## power series representation of a function

Use the formula to compute ln(1.1) correct to 5 decimal places.

$ln(1-x) = - \sum^{\infty}_{n=1} \frac{x^n}{n}$

ln(1.1) = ?

Have no idea what this is asking me to do and no idea where to start.

Thanks!!

2. Originally Posted by mollymcf2009
Use the formula to compute ln(1.1) correct to 5 decimal places.

$ln(1-x) = - \sum^{\infty}_{n=1} \frac{x^n}{n}$

ln(1.1) = ?

Have no idea what this is asking me to do and no idea where to start.

Thanks!!
what happens if you plug in x = -0.1 in the first formula?

you can write out the first few terms of that series, right? can you find an amount of partial sums so that the first five decimal places remain constant? -- ok, that sounded awkward, but hopefully you know what i mean. find the first few partial sums, and see how the value progresses. if the first 5 decimal places are not the same, continue to find more partial sums until it is