Expression 3: StartFraction, left parenthesis, "z" squared minus 1 , right parenthesis sin "z" plus "z" cos "z" Over "z" sin "z" minus "z" squared cos "z" , EndFraction equals StartFraction, 2 Over "z" , EndFraction minus 2 "z" left parenthesis, Start sum from "n" greater than or equal to 1 to , end sum, StartFraction, 1 Over "x" squared minus "z" squared , EndFraction , right parenthesisz2−1sinz+zcoszzsinz−z2cosz=2z−2z∑n≥11x2n−z2