- #1
DDNow
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Homework Statement
All I am trying to do is the basic mathematical induction routine: n=1, n=k, n=k+1 and how n=k proves n=k+1. The problem I am having is with the algebra.
[tex]4+16+64+...+4^{n}=\frac{4}{3}(4^{n}-1)[/tex]
2. Homework Equations and Attempts
For n=1
[tex]4=4[/tex] That's OK
For n=k
[tex]4+16+64+...+4^{k}=\frac{4}{3}(4^{k}-1)[/tex]
For n=k+1 by Substitution
[tex]4+16+64+...+4^{(k+1)}=\frac{4}{3}(4^{(k+1)})[/tex]
To Prove by Adding [tex]K+1[/tex] to [tex]S_{k}[/tex]
[tex]4+16+64+...+4^{k}+4^{(k+1)}=\frac{4}{3}(4^{k}-1)+4^{(k+1)}[/tex]
It took me a minute to figure out how [tex]\frac{4}{3}(4^{k}-1)[/tex] became [tex]\frac{4^{(k+1)}}{3}[/tex], but I got that part.
[tex]= \frac{4^{(k+1)}}{3}+4^{(k+1)}-\frac{4}{3}[/tex]
This is where I am stuck. I gather that I am supposed to multiply [tex]4^{(k+1)}[/tex] by [tex]\frac{3}{3}[/tex], and then combine like terms. I am confused about this because I don't know how to multiply the term by 3 (I probably learned it, I'm just stumped).
Please help me understand what to do next. As long as I can understand how to manipulate the exponential terms with the fractions, I can complete this. Thanks for your time.