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Mathematics 19 Online
OpenStudy (anonymous):

solve

OpenStudy (anonymous):

OpenStudy (anonymous):

1st one: cube root of 64 is 4, cube root of 27 is 3. Ans=4/3

OpenStudy (anonymous):

Simplified 2nd one to x^8=3,814,697,265,625-don't know where to go from there.

OpenStudy (anonymous):

No idea 4 the rest

jimthompson5910 (jim_thompson5910):

For the second one, you don't need to exponentiate. Simply recognize that the 18th root of something to the 18th power is that number (but it's the positive version of that number) Basically, \[\sqrt[18]{x^{18}}=|x|\]

jimthompson5910 (jim_thompson5910):

oops got cut off, but you keep going and you'll basically get positive 5 as your answer for #2

OpenStudy (anonymous):

do you know what to do for the other ones? I didn't understand some of the terms panther was using

jimthompson5910 (jim_thompson5910):

sure, the first one is solved as follows \[\sqrt[3]{\frac{64}{27}}\] \[\frac{\sqrt[3]{64}}{\sqrt[3]{27}}\] \[\frac{\sqrt[3]{4^3}}{\sqrt[3]{3^3}}\] \[\frac{4}{3}\] So \[\sqrt[3]{\frac{64}{27}}=\frac{4}{3}\]

OpenStudy (anonymous):

What about the last two?

jimthompson5910 (jim_thompson5910):

Basically, the cube root of something cubed, is just that something (odd terminology, but it works). Eg: 2 cubed is 8. The cubed root of 8 is 2.

OpenStudy (anonymous):

Right. I understand that question, and i get the second one too now, but I don't understand the last two questions. What are rational exponents and radical notation?

jimthompson5910 (jim_thompson5910):

Third problem \[\sqrt[2]{7}\sqrt[4]{3}\] \[7^{\frac{1}{2}}\cdot3^{\frac{1}{4}}\] \[7^{\frac{2}{4}}\cdot3^{\frac{1}{4}}\] \[\left(7^{2}\cdot3^{1}\right)^{\frac{1}{4}}\] \[\left(49\cdot3\right)^{\frac{1}{4}}\] \[\left(147\right)^{\frac{1}{4}}\] \[147^{\frac{1}{4}}\] \[\sqrt[4]{147}\] So after all that, \[\sqrt[2]{7}\sqrt[4]{3}=\sqrt[4]{147}\]

jimthompson5910 (jim_thompson5910):

Rational exponents are exponents that are fractions. They represent the idea that the expression involves radicals.

OpenStudy (anonymous):

oh. So if you take the square root of something, you're really putting it to the 1/2 power?

jimthompson5910 (jim_thompson5910):

Last question (#4) \[16^{\frac{3}{4}}\] \[\left(16^{\frac{1}{4}}\right)^{3}\] \[\left(\sqrt[4]{16}\right)^{3}\] \[\left(\sqrt[4]{2^4}\right)^{3}\] \[\left(2\right)^{3}\] \[8\] So \[16^{\frac{3}{4}}=8\]

jimthompson5910 (jim_thompson5910):

Yes, taking the square root of any number is the same as raising that number to the 1/2 power. Eg: \[\sqrt{2}=2^{\frac{1}{2}}\]

OpenStudy (anonymous):

Okay I don't understand one thing you're doing- it looks like you're factoring out the exponents? I didn't know you could do that- or, at least, I've never seen it done before... but it seems to serve you well.

jimthompson5910 (jim_thompson5910):

which one are you referring to?

OpenStudy (anonymous):

all of them! It's just a process that I haven't seen yet. What are the can and cannot do's for that? Do you factor them like normal numbers?

jimthompson5910 (jim_thompson5910):

Basically, I'm using the idea that \[\left(x^y\right)^{z}=x^{y\cdot z}\] Essentially this says that you can multiply powers if you raise an exponential expression to another exponent. So I can then use the properties of multiplication (factoring, rearranging, etc) to simplify. Hopefully that clears things up a bit.

jimthompson5910 (jim_thompson5910):

Oh and I'm also using the idea that \[\sqrt[n]{x^m}=x^{\frac{m}{n}}\] which helps me convert to and from radical and exponential notation.

OpenStudy (anonymous):

ok. thanks for explaining

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