When forming the sequences of the polynomial stuff are there any tips or tricks to forming it, or do I just have to be gifted in noticing patterns? What techniques do you use?
-
You must be gifted in studying what mathematicians have done after Maclaurin and Taylor :-)
I mean: you haven't to invent the sand. Like in programming languages, there is a theory and there is an 'art'
suppose you have to Maclaurin f(x) = sin x
let's imagine f(x) like f^0(x)
first derivative as f^1 and so on
f^0 = sin
f^1 = cos
f^2 = - sin
f^3 = - cos
f^4 = sin
there is a "periodicity" that everybody can see
To say nothing of e^x
take f(x) = log(1 + x)
f^0 = log(1 + x)
f^1 = 1/(1+x)
f^2 = -1/(1+x)^2 = - (1+x)^(-2)
f^3 = - (-2)(1 + x)^(-3) = 2(1 + x)^(-3)
f^4 = - 3·2 (1 + x)^(-4)
I bet my hat that
f^n = ( - 1)^(n-1) (n - 1)! (1 + x)^(-n)
so building the series is much easier
(f^n(0) x^n)/n!
log(1+x) = series from n=1 to infinity ((-1)^(n-1) x^n)/n
log 2 = log(1 + 1) = 1 - 1/2 + 1/3 - 1/4 ...
study
exercise
study
I mean: you haven't to invent the sand. Like in programming languages, there is a theory and there is an 'art'
suppose you have to Maclaurin f(x) = sin x
let's imagine f(x) like f^0(x)
first derivative as f^1 and so on
f^0 = sin
f^1 = cos
f^2 = - sin
f^3 = - cos
f^4 = sin
there is a "periodicity" that everybody can see
To say nothing of e^x
take f(x) = log(1 + x)
f^0 = log(1 + x)
f^1 = 1/(1+x)
f^2 = -1/(1+x)^2 = - (1+x)^(-2)
f^3 = - (-2)(1 + x)^(-3) = 2(1 + x)^(-3)
f^4 = - 3·2 (1 + x)^(-4)
I bet my hat that
f^n = ( - 1)^(n-1) (n - 1)! (1 + x)^(-n)
so building the series is much easier
(f^n(0) x^n)/n!
log(1+x) = series from n=1 to infinity ((-1)^(n-1) x^n)/n
log 2 = log(1 + 1) = 1 - 1/2 + 1/3 - 1/4 ...
study
exercise
study