help...what am i doing wrong? The function f(x)=lnx has a Taylor series at a=9. Find the first 4 nonzero terms in the series, that is write down the Taylor polynomial with 4 nonzero terms.

i tried ln(9)+1/9-1/9^2+2/9^3 and that's not working...

Question

help...what am i doing wrong?  The function f(x)=lnx has a Taylor series at a=9. Find the first 4 nonzero terms in the series, that is write down the Taylor polynomial with 4 nonzero terms. 

i tried ln(9)+1/9-1/9^2+2/9^3 and that's not working...

koikkara · Answer

forgot all these..sorry..

phi · Answer

see https://en.wikipedia.org/wiki/Taylor_series#Definition I think you left out the (x-9)^n terms

phi · Answer

and the divide by n! ?

the first 3 terms are
$$\ln(9) + \frac{(x-9) }{9} -\frac{ (x-9)^2 }{2\cdot 9^2}$$

anonymous · Answer

ok, let me try that.  i've seen so many different formulas for stuff..

anonymous · Answer

ok.  thanks, @phi.  that worked.  i was using the wrong formla