Expression 4: "f" left parenthesis, "x" , right parenthesis equals 3 "x"fx=3x
4
Expression 5: StartFraction, "b" minus "a" Over "n" , EndFraction Start sum from "k" equals 0 to "n" minus 1, end sum, "f" left parenthesis, "a" plus StartFraction, "b" minus "a" Over "n" , EndFraction times "k" , right parenthesisb−ann−1∑k=0fa+b−an·k
5
Expression 6: StartFraction, "b" minus "a" Over "n" , EndFraction Start sum from "k" equals 1 to "n" , end sum, "f" left parenthesis, "a" plus StartFraction, "b" minus "a" Over "n" , EndFraction times "k" , right parenthesisb−ann∑k=1fa+b−an·k