Expression 2: "d" left parenthesis, "t" , right parenthesis equals alpha "c" times left parenthesis, "u" left parenthesis, "t" plus StartFraction, 1 Over 2 "c" , EndFraction , right parenthesis minus "u" left parenthesis, "t" minus StartFraction, 1 Over 2 "c" , EndFraction , right parenthesis , right parenthesisdt=αc·ut+12c−ut−12c