Expression 3: "y" Subscript, 1 , Baseline equals StartFraction, "e" Superscript, "x" Subscript, 1 , Baseline , Baseline Over "e" Superscript, "x" Subscript, 1 , Baseline , Baseline plus "e" Superscript, "x" Subscript, 2 , Baseline , Baseline plus "e" Superscript, "x" Subscript, 3 , Baseline , Baseline , EndFraction Has graph. To audio trace, press ALT+T.y1=ex1ex1+ex2+ex3