運算式 3: "T" left parenthesis, "x" , right parenthesis equals Start sum from "n" equals 0 to "k" , end sum, StartFraction, "D" left parenthesis, "a" , right parenthesis left bracket, "n" plus 1 , right bracket Over "n" ! , EndFraction left parenthesis, "x" minus "a" , right parenthesis Superscript, "n" , BaselineTx=k∑n=0Dan+1n!x−an