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Mathematics 20 Online
OpenStudy (seratul):

How do I solve this problem?

OpenStudy (seratul):

\[\sqrt[56]{9^{70}}\]

OpenStudy (seratul):

I would assume I do 9^70, but i'll get some big number.

OpenStudy (seratul):

The answer to this is \[9\sqrt{3}\] I just don't know how to get there.

OpenStudy (steve816):

Hey, the following radical can be expressed as\[\Large 9^{\frac{ 70 }{ 56}}=9^{\frac{ 5 }{ 4 }}\]

OpenStudy (seratul):

Oh, I know that I can make this into 9^(70/56), but is there any other possible way?

OpenStudy (seratul):

Oh, is that the only way I can solve this type of question? By making it into exponents? Is it possible for me to rewrite it again as \[\sqrt[4]{9^{5}}\] and somehow solve like that?

OpenStudy (steve816):

Yeah, you should be able to intuitively change the forms of radicals into exponents.

OpenStudy (steve816):

And yes, you can rewrite it like that.

OpenStudy (mathmale):

What do you mean by "solve this problem?" There's nothing here to solve. I think you mean "simplify," not "solve."\[\sqrt[56]{9^{70}}=9^{\frac{ 70 }{ 56 }}=9^{\frac{ 5 }{ 4 }}\]

OpenStudy (mathmale):

You could re-write this last result:\[9^{\frac{ 5 }{ 4 }}=[3^2]^{\frac{ 5 }{ 4 }}\]

OpenStudy (mathmale):

This can be reduced. Try it.

OpenStudy (steve816):

In order to further reduce it, you can re-write it as\[\Large 9^\frac{ 4 }{ 4 }*9^\frac{ 1 }{ 4 }=9\sqrt{3}\]

OpenStudy (seratul):

Alright. We multiply 2 and 5/4 correct? We should get 10/4=5/2 as the exponent. So... \[3^{5/2}\]

OpenStudy (seratul):

@steve816 how did you get that?

OpenStudy (seratul):

Isn't it a^n times a^m?

OpenStudy (steve816):

Nope, I think you are thinking of\[\Large (a^n)^m=a^{n*m}\]

OpenStudy (seratul):

\[a ^{n}* a ^{m} = a^{n+m}\]

OpenStudy (steve816):

Ohh wait, my bad

OpenStudy (steve816):

You're correct about that.

OpenStudy (seratul):

How did you get \[\Large 9\sqrt{3}\]

OpenStudy (unklerhaukus):

\[\sqrt[56]{9^{70}}\\ =\sqrt[56]{(3^2)^{70}}\\ =\sqrt[56]{3^{140}}\\ = 3^{140/56}\\ =3^{112/56}\times3^{28/56}\\ =3^2\times3^{1/2} \]

OpenStudy (seratul):

I'm still a little confused on how that results in 9 radical 3. But i'll just ask my teacher for a little more clarification. Thanks @steve816 @mathmale and @UnkleRhaukus

OpenStudy (unklerhaukus):

\[\sqrt[56]{9^{70}}\\ =\sqrt[56]{(3^2)^{70}}\\ =\sqrt[56]{3^{140}}\\ =\sqrt[56]{3^{112}\times3^{28}}\\ =\sqrt[56]{3^{112}}\times\sqrt[56]{3^{28}}\\ =3^{112/56}\times3^{28/56}\\ =3^{2}\times3^{1/2}\\ =9\times\sqrt3\]

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