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Maths help c2

In the picture I cannot get the expression I have differentiated into the form they want in the question ... Any ideas?:frown: thanks :smile:

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Reply 1
missing an X after 1/2(2)-insert X-^-1/2
Reply 2
Original post by Booyah
missing an X after 1/2(2)-insert X-^-1/2


opps my bad! i am still unsure of how to do it though :/
Reply 3
Original post by madfish
opps my bad! i am still unsure of how to do it though :/


write X^-1/2 - 9X^-5/2 into fractions. See what you can do from there
Reply 4
Original post by Booyah
write X^-1/2 - 9X^-5/2 into fractions. See what you can do from there


euggghh!!!! I cannot do it :frown:
Reply 5
Original post by madfish
euggghh!!!! I cannot do it :frown:


the answer's denominator is X^2X^1/2

which is X^5/2 as 2+ 1/2 is 5/2 which links to 9X^5/2

Now do you have any ideas on what to do for X^-0.5?

And don't worry, it is just practice, I averaged Cs+D's all year long for maths but with enough practice I got an A in the actual exam :smile:
(edited 11 years ago)
Reply 6
Original post by Booyah
the answer's denominator is X^2X^1/2

which is X^5/2 as 2+ 1/2 is 5/2 which links to 9X^5/2

Now do you have any ideas on what to do for X^-0.5?

And don't worry, it is just practice, I averaged Cs+D's all year long for maths but with enough practice I got an A in the actual exam :smile:


I really have no idea about this question :frown: sorry I sound so stupid :colondollar:

yea these are the rotten last questions on the differentiation chapter.. :frown: and thanks so much :smile: !
Reply 7
Original post by madfish
I really have no idea about this question :frown: sorry I sound so stupid :colondollar:

yea these are the rotten last questions on the differentiation chapter.. :frown: and thanks so much :smile: !


Alright then, this is a GCSE skill which derives on multiplying something by 1 doesn't change the value.

Take 1/2 if we multiply it by 4/4 it becomes 4/8 which is still 1/2

So if we use this but with X^2/X^2 and multiply X^-1/2 we will still get X^1/2 but in the form X^2/X^5/2 which is infact:

X^2/(X^2)(X^0.5). Now you can subtract the other fraction 9/(X^2)(X^0.5)

Quote any part you don't understand (I can't use that maths number thingy though...)
(edited 11 years ago)
Reply 8
Original post by Booyah
Alright then, this is a GCSE skill which derives on multiplying something by 1 doesn't change the value.

Take 1/2 if we multiply it by 4/4 it becomes 4/8 which is still 1/2

So if we use this but with X^2/X^2 and multiply X^-1/2 we will still get X^1/2 but in the form X^2/X^5/2 which is infact:

X^2/(X^2)(X^0.5). Now you can subtract the other fraction 9/(X^2)(X^0.5)

Quote any part you don't understand (I can't use that maths number thingy though...)

Okay I am at the part where I have differentiated to get 2/x^7/2 + 6/x^3/2

where do i go from here?:colondollar:
Reply 9
Original post by madfish
Okay I am at the part where I have differentiated to get 2/x^7/2 + 6/x^3/2

where do i go from here?:colondollar:


The differential is X^-0.5 - 9X^-2.5

as the powers are negative
img019.jpgHere you go! That integral sign meant to be dy/dx :P I don't know why I did that D:
(edited 11 years ago)
Reply 11
Original post by Lifestalker
img019.jpgHere you go! That integral sign meant to be dy/dx :P I don't know why I did that D:


thanks very much :smile:
do you think that is a hard question for as level? bearing in mind this is as level!
Reply 12
Original post by madfish
thanks very much :smile:
do you think that is a hard question for as level? bearing in mind this is as level!
Pretty standard differentiation question tbh, something you'd expect in the exam for algebra differentiation, they can't just give you simple ones otherwise that's easy marks :P
Reply 13
Original post by Lifestalker
img019.jpgHere you go! That integral sign meant to be dy/dx :P I don't know why I did that D:

one question... how do you get the numerator of 9 to be that? I get it to be (sqrtx)^5
Yeah, I'm at your level too!
I, personally, didn't find it difficult, but I can see where you would have trouble (it's pretty weird changing the denominator, actually).
I think I would've had trouble without it saying "if f'(x) = whatever".
If you practice enough, it'll become second nature, so, at the moment, it may seem difficult, but give it time :wink:
Reply 15
Original post by Robbie242
Pretty standard differentiation question tbh, something you'd expect in the exam for algebra differentiation, they can't just give you simple ones otherwise that's easy marks :P

dude, that is harder than standard questions... just saying
The numerator 9?

I did 6*(-[3/2])
or rather: 6*(-1.5) = -9
(edited 11 years ago)
Reply 17
Original post by madfish
dude, that is harder than standard questions... just saying
Well it is unlikely they'll say y=3x^4+3x^3+2x+1 find the maximum value that's like c2 differentiation exercise 9b) stuff like 9c) 9d) and mixed exercises they're more likely to ask. Regardless though if your not familiar with indices and other things used here it can be tough
Reply 18
Original post by Lifestalker
The numerator 9?

I did 6*(-[3/2])
or rather: 6*(-1.5) = -9


got it now dude, cheers for that! Love it when someone puts the solutions up! Makes me learn it a lot easier :smile:
Reply 19
Original post by Robbie242
Well it is unlikely they'll say y=3x^4+3x^3+2x+1 find the maximum value that's like c2 differentiation exercise 9b) stuff like 9c) 9d) and mixed exercises they're more likely to ask. Regardless though if your not familiar with indices and other things used here it can be tough


I am doing these questions from a textbook I bought, not the edexcel one... I have done all the edexcel ones they are quite easy tbh lol

and yea, I am going to practice C1 all day tomorrow do all then indicies questions etc :smile:

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