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Mathematics 20 Online
OpenStudy (anonymous):

What is the solution to the equation?

OpenStudy (anonymous):

\[3^{5}\sqrt{(x+2)^{3}}+3=27\]

OpenStudy (anonymous):

@jim_thompson5910

jimthompson5910 (jim_thompson5910):

is that 5 for the 3? or is it for the root?

OpenStudy (anonymous):

I have no idea... let me screen shot it and post.

jimthompson5910 (jim_thompson5910):

alright

OpenStudy (anonymous):

Never mind it wont let me screen shot it. its posted all together though.

jimthompson5910 (jim_thompson5910):

the thing is that I wonder if it is \[\Large 3\sqrt[5]{(x+2)^{3}}+3=27\] notice how the 5 is the index for the radical

OpenStudy (anonymous):

I think its supposed to be in the index, because thats how it is in the book, and they talked about the index in our last lesson.

jimthompson5910 (jim_thompson5910):

ok so first thing you do is subtract 3 from both sides

OpenStudy (anonymous):

from every number?

jimthompson5910 (jim_thompson5910):

like this \[\Large 3\sqrt[5]{(x+2)^{3}}+3=27\] \[\Large 3\sqrt[5]{(x+2)^{3}}+3{\color{red}{-3}}=27{\color{red}{-3}}\] \[\Large 3\sqrt[5]{(x+2)^{3}}+0=24\] \[\Large 3\sqrt[5]{(x+2)^{3}}=24\]

OpenStudy (anonymous):

Oh okay! Thats easy!

OpenStudy (anonymous):

Now what?

jimthompson5910 (jim_thompson5910):

now we divide both sides by 3 to move that "3" on the left side (outside the radical) to the right side

OpenStudy (anonymous):

Now divide by 3 on both sides. Then you have both sides to the power of 5.

jimthompson5910 (jim_thompson5910):

\[\Large 3\sqrt[5]{(x+2)^{3}}=24\] \[\Large \frac{3\sqrt[5]{(x+2)^{3}}}{\color{red}{3}}=\frac{24}{{\color{red}{3}}}\] \[\Large \sqrt[5]{(x+2)^{3}}=8\]

OpenStudy (anonymous):

Okay, Got it. Now what?

jimthompson5910 (jim_thompson5910):

how do we undo that fifth root? what must we do to both sides?

OpenStudy (anonymous):

um...divide them?

jimthompson5910 (jim_thompson5910):

not quite

jimthompson5910 (jim_thompson5910):

5th powers undo 5th roots

jimthompson5910 (jim_thompson5910):

we raise both sides to the 5th power \[\Large \left(\sqrt[5]{(x+2)^{3}}\right)^{ {\color{red}{5}} }=8^{\color{red}{5}}\] \[\Large (x+2)^{3} =??\]

OpenStudy (anonymous):

uhhh.... 32,768?

jimthompson5910 (jim_thompson5910):

yes

jimthompson5910 (jim_thompson5910):

\[\Large (x+2)^{3} =32768\]

jimthompson5910 (jim_thompson5910):

now we apply the cube root to both sides \[\Large (x+2)^{3} =32768\] \[\Large \sqrt[3]{(x+2)^{3}} =\sqrt[3]{32768}\] \[\Large x+2 =32\]

jimthompson5910 (jim_thompson5910):

since \[\Large 32^3 = 32768\] we just take things in reverse to say \[\Large \sqrt[3]{32768} = 32\]

OpenStudy (anonymous):

So thats all, right? Because it simplifys to 32?

jimthompson5910 (jim_thompson5910):

well x+2 = 32, but we want x itself

OpenStudy (anonymous):

x=30?

jimthompson5910 (jim_thompson5910):

yes

OpenStudy (anonymous):

is that the final answer?

jimthompson5910 (jim_thompson5910):

yes

OpenStudy (anonymous):

thank you!

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