How do you evaluate the function f(x)=e^xf(x)=ex at the value of x=3.2x=3.2?

1 Answer
Jul 28, 2017

f(3.2) approx 24.53253f(3.2)24.53253

Explanation:

f(x) = e^xf(x)=ex

e^xex is a transcendental function meaning that is both irrational and cannot be expressed in terms of a finite sequence of the algebraic operations of addition, multiplication, and root extraction.

Hence, e^xex can never (except in the trivial case x=0x=0) be expressed as a fraction, the root of any polynomial with rational coeffients or the sum of any finite series. Thus, it can only ever be approximated by a number of any base.

Several definitions of e^xex exist. Two of the most well known of these are:

e^x = lim_(n->oo) (1+x/n)^n (limit known to exist forall x in RR)

e^x = sum_(n=0) ^oo (x^n)/(n!) (sum known to converge forall x in RR)

From the second definition above we can approximate e^3.2 as a decimal as follows:

e^3.2 = 1 + 3.2 + 3.2^2/(2!)+ 3.2^3/(3!) + 3.2^4/(4!) + .......

approx 24.53253