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# C2: Simplifying indices? watch

1. (Original post by kiiten)
Sorry its the first expression. I differentiated 3x ^ 5/2 - 12x ^ 3/2 + 12x ^ 1/2
Correct.

Dy/dx = 15/2x ^ 3/2 - 18x ^ 1/2 + 6x ^ -1/2
Again, correct.

So, what do you get when you substitute x=3 into this? You may find it helpful to write down

15/2 * (3)^(3/2) - 18 * 3^(1/2) + 6* 3^(-1/2) and then simplify from there by pulling out common factors.
2. (Original post by Zacken)
Correct.

Again, correct.

So, what do you get when you substitute x=3 into this? You may find it helpful to write down

15/2 * (3)^(3/2) - 18 * 3^(1/2) + 6* 3^(-1/2) and then simplify from there by pulling out common factors.
38.971... - 31.176... +3.464...

= 11.3
3. (Original post by kiiten)
38.971... - 31.176... +3.464...

= 11.3
That's correct.
4. (Original post by Zacken)
That's correct.
Thanks . - Its really annoying when the answers in the textbook are wrong
5. (Original post by Zacken)
That's correct.
Stop using that
6. (Original post by tinkerbella~)
Stop using that
you are the second person to change the username in the account....
do you have to ask? is it easy?
7. (Original post by TeeEm)
you are the second person to change the username in the account....
do you have to ask? is it easy?
I emailed them and some lovely lady Katy did it for me.
8. (Original post by tinkerbella~)
I emailed them and some lovely lady Katy did it for me.
I thought it was a DIY job from the settings.
Thanks
9. (Original post by TeeEm)
I thought it was a DIY job from the settings.
Thanks
They said you need a good reason but they did mine so idk. Thinking of changing?
10. (Original post by tinkerbella~)
They said you need a good reason but they did mine so idk. Thinking of changing?
Nope
too much attachment ...
never changed my Avatar either.

... but it is nice to know how it is done.
11. (Original post by TeeEm)
Nope
too much attachment ...
never changed my Avatar either.

... but it is nice to know how it is done.
I think you should reverse your name : mEeeT

Yeah they usually allow you to change your name. I was once notnek01.
12. (Original post by notnek)
I think you should reverse your name : mEeeT

Yeah they usually allow you to change your name. I was once notnek01.
I guess it will still be recognizable ...

My real name (surname) spells a famous Iraqi backwards ...
13. (Original post by TeeEm)
I guess it will still be recognizable ...

My real name (surname) spells a famous Iraqi backwards ...
14. (Original post by TeeEm)
Nope
too much attachment ...
never changed my Avatar either.

... but it is nice to know how it is done.
Good, it'd take me too long to adjust if you did. I get confused very easily.
15. (Original post by tinkerbella~)
Good, it'd take me too long to adjust if you did. I get confused very easily.
no worries

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