Вираз 5: "f" Subscript, "r" , Baseline left parenthesis, "x" , right parenthesis equals "f" Subscript, "c" , Baseline left parenthesis, "x" , right parenthesis times "r" Subscript, "i" , Baseline times "f" Subscript, "s" "p" "e" "e" "d" , Baseline left parenthesis, "x" , right parenthesisfrx=fcx·ri·fspeedx