I don't get the space alien connection. Looks like a homework question.Two hints : product and chain rule. Undoubtedly, then, the emissions requirements became still more stringent, as evidenced by universal use of cats? Somewhere along these lines, in recent years, injection of fresh air into the exhaust gas stream disappeared (the "smog" pump) on the last 4 vehicles I have owned. It is for discovering that which is true and real. Originally Posted by river_rat L...