Monday, 29 April 2013

algebra precalculus - What is the plot of f(x)=1+sqrtlog10cos(2pix)



I'm inspecting a function as in the title, and tried to plot it and then compare my result with graphing tools which lead me to confusion.




Is it true that the plot of f(x)=1+log10cos(2πx) is just a set of points (x,y)=(n,1);nZ




Inspecting the domain one may see that
log10cos(2πx)0cos(2πx)1



But cosx[1,1] therefore cos(2πx) must be equal to 1 in order to satisfy the above, and that is only possible in xZ.



The reason I'm asking is because neither Desmos nor W|A is plotting it the way i expected.


Answer



You are right: the domain of f is the set Z and the graph of f is given by



{(x,f(x)):xZ}={(n,1):nZ}.



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