Expression 4: left parenthesis, "x" Subscript, 9 , Baseline left parenthesis, "t" , right parenthesis , "y" Subscript, 9 , Baseline left parenthesis, "t" , right parenthesis , right parenthesisx9t,y9t
domain t Minimum: 00
less than or equal to "t" less than or equal to≤t≤