SDN Members don't see this ad. (About Ads) I guess they could, but when would you know to make the exponent negative? I don't really understand why they would have - exponents...i guess negative means that substrate simply decreases the rate? how would that appear in a problem? apparently, the exponents can also be fractions...that makes a lil more sense since there's still positive effects on the rate. so, - exponents would simply imply negative effects on the rate?