In the above, the base 7 is changed first to 10, then to e, then to 134, all of them yielding the same answer as the original (whether using for graphing or any other mathematical use).īTW, you need to do the same thing in your scientific / graphing calculator to get an accurate graph or calculation that involves a log to a base other than 10 or e. So, log base 7 of x = log x / log 7 = ln x / ln 7 = Ln x means log base e of x (where e = 2.71. Log base b of a =(log base c of a) /(log base c of b). The idea is that (changing the base from b to c) you change the base but divide by the log (new base) of the old base. It (mine above) uses the change-of-base formula. Y = 3/2 times log x which is not the same as y = log (base 3/2) of x. If you don't understand get out an intermediate / college algebra or precalculus book. Anonomac, You're right, it is easy, but the object is to first get it right, then get it easy.
