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# Definite integrals and finding "z" Watch

1. I identified that x^2 would become

But even with me substituing x for z; to give z^3/3-9=0

I remain unsure how to proceed further.
2. (Original post by apronedsamurai)

I identified that x^2 would become

But even with me substituing x for z; to give z^3/3-9=0

I remain unsure how to proceed further.
Now solve for Z.
3. (Original post by apronedsamurai)

I identified that x^2 would become

But even with me substituing x for z; to give z^3/3-9=0

I remain unsure how to proceed further.
Is there an actual question
4. (Original post by uberteknik)
Now solve for Z.

I thought it was z^3/3=9

I then just took an educated guess; that it was 3; because 3^3=27/3=9

But that was more guesswork and intuition, I am wondering is this like approximiate roots, i.e. you use the trial and error method, or is there a more concrete method/trick to be used
5. (Original post by apronedsamurai)
I thought it was z^3/3=9

I then just took an educated guess; that it was 3; because 3^3=27/3=9

But that was more guesswork and intuition, I am wondering is this like approximiate roots, i.e. you use the trial and error method, or is there a more concrete method/trick to be used
Why would you need to guess

Z^3/3 = 9

Multiplying both sides by 3 gives

Z^3 = 27

Cube rooting both sides gives

Z = 3
6. I wasn't sure that was the approach to take, that is why I am asking....
7. (Original post by apronedsamurai)
I wasn't sure that was the approach to take, that is why I am asking....
TenofThem gave you the approach, it's simple manipulation, multiplying, taking cube roots etc etc. You're trying to isolate the z term.
8. (Original post by apronedsamurai)
I thought it was z^3/3=9

I then just took an educated guess; that it was 3; because 3^3=27/3=9

But that was more guesswork and intuition, I am wondering is this like approximiate roots, i.e. you use the trial and error method, or is there a more concrete method/trick to be used
There's no "guesswork" involved in this - it's just basic GCSE rearrangement.

If then and so

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