Find a power series expansion for the function 1 f (x ) = x2 - 4' using each of the following methods: a. By starting with the geometric series and applying a suitable substitution. b. By first finding numbers A and B such that A B f (2) = + x - 2 x + 2' then finding a power series expansion for each summand, and then adding the results. c. By first writing f(x) as a product, f(2) = x - 2 x+2' then finding a power series expansion for each factor, and then multiplying the results