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Mathematics 21 Online
OpenStudy (anonymous):

I am trying to figure this section out for myself before the teacher lectures on it so if some can explain this one to me would be great

OpenStudy (anonymous):

g(f(-3)) f(x)=\[\sqrt[3]{x+1}\] \[g(x)=4x^{2}-x\]

OpenStudy (anonymous):

Well first sub in the value of -3 into f(x) and see what you get

hartnn (hartnn):

can you first find f(-3) ? just put x=-3 in f(x)

OpenStudy (anonymous):

\[\sqrt[3]{-3+1}=\sqrt[3]{-2}\] ?

OpenStudy (anonymous):

Yeah that look about right

OpenStudy (anonymous):

Then you put that into the place of x in g(x), and solve the equation

OpenStudy (anonymous):

so \[4\sqrt[3]{-2}^{2}-\sqrt[3]{-2}\]

OpenStudy (anonymous):

Yeah, although that looks really messy, but it should be the right answer

OpenStudy (anonymous):

the answer in the book says its \[4\sqrt[3]{4}+\sqrt[3]{2}\]

OpenStudy (anonymous):

Yes they are the same form,\[\sqrt[3]{-2}^{2}=\sqrt[3]{4}\] since you can drop the square in

OpenStudy (anonymous):

ah yes ok get it

OpenStudy (anonymous):

Do you get the second part also?

OpenStudy (anonymous):

the - and - signs = + ?

OpenStudy (anonymous):

Yes, since the minus sign is technically -1, you can bring that inside the square root and multiply it with -2, where negative and negative make positive

OpenStudy (anonymous):

thanks :)

OpenStudy (anonymous):

No probs :D

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