expand f(x)= xcosx

up to x^3

differentiating many times my expansion is

http://quicklatex.com/cache3/ql_06c3...37e773c_l3.png

to find an approximate value for

http://quicklatex.com/cache3/ql_277f...81c2edb_l3.png

do I just plug in the limit values and evaluate as below?

http://quicklatex.com/cache3/ql_6c07...1ea3a3f_l3.png