What is the Rule of 72, and how do you calculate it? A An estimate for the number of years it will take for an investment to double, calculated by subtracting the rate of return (interest rate) from 72. B An estimate for the number of years it will take for the rate of return to double, calculated by dividing 72 by the length of time the principal amount is held on deposit. C An estimate for the number of years it will take for the principal deposit to double, calculated by dividing 72 by the rate of return. D An estimate of the time it will take you to graduate from a 4-year college, you divide 72 by the total number of courses you need t

like many students at university, you may be unhappy about the results you attain in exams. you may feel that even with all you are doing there must be something more -- or different-- you could be doing to get better grades. we have all at some time or other heard of that student who only studies a couple of hours for final exams and scores a's every time. we stand in awe of those who seem to breeze through without undue effort and seem to need very little in the way of studying to nail an exam. the reasons for success, in what i think are the vast majority of cases, are less esoteric than many students think: successful students consistently apply a series of productive strategies with view to attaining clearly identified learning and grade goals throughout the academic term.

to answer your question:

f(x)= a^x.  if x=0, f(x)=1  if x=1, f(x)=a  if x=1, f(x)=a^a

its not minor, got it wrong.