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OpenStudy (anonymous):
18
42
80
81
320
OpenStudy (kirbykirby):
Ok so it's a matter of breaking it down:
OpenStudy (kirbykirby):
You need to be familiar with the laws of exponents.
\[10^{\frac{k}{2}+1}\]... do you know the law \(a^b*a^c=a^{b+c}\)
OpenStudy (anonymous):
yes
OpenStudy (kirbykirby):
so here it's the same idea, but here a=10 and "k/2"=b and "1"=c
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OpenStudy (kirbykirby):
can you re-write it using the law?
OpenStudy (anonymous):
10^(k/2)+ 10^1
OpenStudy (kirbykirby):
almost... just replace your addition + with a multiplication
OpenStudy (anonymous):
10^(k/2) x 10^1
OpenStudy (kirbykirby):
yes, now there is another law \[(a^B)^C=a^{BC}\] and we can apply it to \[10^{\frac{k}{2}}\] by noticing that \[\frac{k}{2}=k*\frac{1}{2}\]
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OpenStudy (anonymous):
so 320?
OpenStudy (kirbykirby):
Nope =\ If you re-write \[10^{\frac{k}{2}}=10^{k*\frac{1}{2}}\]
OpenStudy (kirbykirby):
You can see that you can say \((10^k)^{\frac{1}{2}}\)
OpenStudy (anonymous):
First we notice the following:\[\bf 10^{\frac{k}{2}+1}=10^{\frac{k}{2}}(10)=(10^k)^\frac{1}{2}(10)=10\sqrt{10^k}\]We know that \(\bf 10^k=64\), so plug that in and evaluate.