Expert: Sherman D. - 5/5/2005

Question
Hi, Mr. Sherman, I figured you could show me how to do this question.

My question is How do you graph f(x)=log4x on the graphing calculator TI-83+, and is there any way I could get an easy answer using my TI-83 calculator on this equation: log2 16 or 2 to what power gives 16?

Thanks Sherman

Answer
since you can't do bases, here is what you should do

instead of doing log(base 4)x, you should type
(log(x))/(log(4))

info found at http://people.hofstra.edu/faculty/Stefan_Waner/RealWorld/calctopic1/logs.html

that is what i do to type it in places like www.calculator.com and www.quickmath.com because just like the graphing calculator, it doesn't do bases.

as for log(base 2)16, you can type it in as
(log(16))/(log(2)) to get 4.

to do it like 2^x = 16, you will have to graph it as 2^x, then look to where y = 16. But the easiest way to graph it would be to type it in as (2^x) - 16, and see where the line crosses at the x-axis.

You can use calculator.com to do this. Just leave out the y = part, or the graph will not show up, because since the graph is already in y = form, you don't need to put the y = part. If you go to quickmath.com you don't have to worry about having it in y = form, you can have it in as 2x + 5y = 10 if you like, it will graph it like that.