Tutorial Exercise Find a power series for the function centered at c and determine the interval of convergence 3 f x 3x 2 C 6 Step 1 Rewrite the original function f x Step 2 f x 3 3x 2 18 18 20 3x18 20 3 3 after adding and subtracting 18 in the denominator as follows 3x 2 18 3 x 6 Divide the numerator and denominator of the function f x 20 20 x by 20 to put it in the form of a geometric series 6