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A dump of our free Chat sessions, in case it is useful. It excludes white boards used during paid sessions.
tutor3 : Hello Student, May I help you with your Math problems? student : Yes please student : I'm trying to formulate the equation for an exponentially decaying function. student : Time is a function of Concentration, so we could write this variable as T(c) student : Otherwise I don't know what else to add. student : I guess the equation would look like this: student : T(c)=a(b^t) student : But I don't know what "a" and "b" are. I don't need numbers per se... tutor3 : so you need to know what are a and b ? student : Yes, I need two variables. For example, maybe "a" is the initial T value when C = 0. student : We can use the variables "a" and "b", I just need to know what they represent. student : I'm just looking at the wikipedia page :p http://en.wikipedia.org/wiki/Exponential_decay tutor3 : Exponential functions are closely related to geometric sequences. A geometric sequence of numbers is one in which each successive number of the sequence is obtained by multiplying the previous number by a fixed factor m. An example is the sequence {1, 3, 9, 27, 81, â€¦}. If we label the numbers in the sequence as {y0, y1, y2, â€¦} then their values are given by the formula: yn = y0 Â· m n. The geometric sequence is completely described by giving its starting value y0 and the multiplication factor m. For the above example y0 = 1 and m = 3. Another example is the geometric sequence {40, 20, 10, 5, 2.5, â€¦} for which y0 = 40 and m = 0.5.
The exponential function is simply the generalization of the geometric sequence in which the counting integer n is replaced by the real variable x. We define an exponential function to be any function of the form: y = y0 Â· m x. tutor3 : yn means y suffix n and all the mn will be m^n student : I'll hold my breath and wait for you to bring this horse back on track :p student : (what does the "say" button do?) student : It would be better if you typed, then posted, then typed, then posted. tutor3 : 'a' is basically the y intercept of the exponential curve b^x and 'b' is the common factor of the given series and x is the number of terms in the series student : Okay student : Let me explain this a little better: student : I was examining the time it took for an enzyme to break down a substrate. student : I was specifically looking at how the concentration of that substrate affects the time. tutor3 : Please note, due to lack of resources, we can only do 1 problem FREE in 24 hours period. You can always come back tomorrow for another free problem. Please, tell your friends about our free service  1 free in 24 hours student : Logically, if the concentration of substrate = 0, then a = 0 tutor3 : you can mail us your sum with your deadline Fax your homework to 2063398302. or, email to *****@aafter.com. Include your email and phone number. student : Sorry, a = infinity student : Is this all the time I get? tutor3 : no u get helped for once in 24 hours student : Can you visualize the graph I am describing? student : As lim(x) approaches 0, y approaches infinity student : And as lim(x) approaches infinity, y approaches 0. student : What kind of graph is that? student : Inverse, right? tutor3 : am sorry we have other students to help please come back tomorrow or mail us your sum student : Okay, God bless you. tutor3 : god bless you too
