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Yeah x=0 makes sense, its the x value for which dy/dx=0. Well thanks again Mathyperson always at hand to give a well explained answer.
Excellent Mathsyperson, extremely helpful as usual, you helped clear that up for me! Thank you very much! Just to clarify, in your example, x=o is a global minimum and there is no global maximum?
I have a question which asks me to calculate the global maximum and global minimum of
y=e^(-x)cos(x)
Well i read a maths book explaining how to calculate them (by working out the local maxima and minima, and then putting these values and the ends of the domain back into f(x) to work out the greatest value(global maxima) and least value(global minima). The domain in my case is
.So the domain is greater than
and less then
so i was wondering can i include
in the calculation of the global minima?Thanks (sorry for the mistakes in my post!)
Ricky makes a very good point. It is extremely likely it is a scam, and you will end up the looser. You cannot compare a mistake of £10 with 6.2 million dollars. I think you should think again about going ahead with this.
Welcome Flamen, you have come to the right place, everyone is extremely helpful on this forum!
Amazing photos MathsIsFun, im also keen on astronomy, its fascinating!
Welcome Dan
TheDude makes a good point.
The answer is plus or minus 4.
Thank you all for the welcomes!
The clue mathsyperson gave you was a very useful one, if you were still unable to get the solution, these are the answers i got:
andk=26/7 and k=30/7 for the other solution.
What might help you is actually drawing the sketch (possibly to understand whats going on a bit better)
Hi there,
I'm Technique09, I've recently joined this forum, and I think it is great. I'm here to give help (when possible) and ask for help, as many people here are far more experience than me. I want to become a better problem solver, and I'm hoping practicing here will help me.
Technique09
Yes i have heard of Kosovo, i have some friends from there. Im from London. Are you currently studying in University?
im 18, how old are you?
Excellent, you are bright for your age. How old are you? and where are you from?
Thanks again G_Einstein, what you wrote has helped me alot, the problem became much clearer to me, once i saw your method, to be honest i should have got the answer, i wasnt thinking enough.
PS The esence of resolving math problems is to use the simple logic with numbers and to think,what we've got and what not,what do we need to resolve the problem.Everything goes with logic
That makes a lot of sense, and i will think about it when tackling problems. Im quite sure
works, i think you just made a mistake in not considering the extra . However, your method was good and it helped me alot! Thanks also for telling me about the "Math" Button, it shall make my writing neater in the future!Ive just started my first year at uni. What level of maths are you studying?
Excellent post G_Einstein, it helped me alot. I got up to part (6) by myself, but what you did after that was clever, putting everything in terms of A.
However i do have a few questions regarding your method.
1) From B^2=16 how did you know B=4 and D=4? Couldnt they both be -4? I had trouble determining whether they were positive or negative.
2)Once you collected like terms i think you made a mistake when writing 4(x^2) - (A^2)(x^2)= -4(x^2), i think it should have been 4(x^2) - (A^2)(x^2) + 4(x^2)= -4(x^2), i think you accidentally missed the plus four x squared.
The solution you wrote was also wrong, firstly you missed the x on the root 8, and secondly its root 12x.
I think the solution is [(x^2) + (12^0.5)x + 4] [(x^2) - (12^0.5)x +4]
Thank you very much G_Einstein, your method past part (6) was clever, i should have thought of it!
PS How do you write your maths in that format?
yeah i understand what you mean, thanks luca-deltodeco and mathsyperson for helping clear that up for me.
For some reason i cannot seem to get the answer to this.
Express (x)^4 - 4(x^2) +16 in the form
(x^2 + Ax + B) (x^2 +Cx + D)
What i tried to do is to expand the two brackets above out and equate coefficients, however i couldnt get the right answer i kept on getting +4(x^2).
Can anyone suggest another possible way of doing it that works?
Thanks
Ahh ok, thanks made that much clearer for me. So basically, the number 36 in the question means nothing, however if a similar sort of question was applied to a real life problem, then it would have a meaning?
That did make a lot of sense, i was thinking about the second derivative in exactly the same way as you are. However, in the question i was asking what the significance of the 36 was, what does the actual number represent? I understand how to get that number, but was is it showing? I hope im making sense in the questions im asking, its just been bugging me thinking about it.
PS Thanks for noting the mistakes with my brackets, it was careless.
Hi there, i was wondering if someone could help me understand the second derivative in more detail.
Well, i understand that the second derivative means the rate of change of the rate of change, however what does it mean once you use it to solve problems? Here is my example:
"Find the stationary points of f(x)= x^4 - (6x)^2 + 8x and hence classify as local maxima, local minima or point of inflection.
f'(x)= (4x)^3 - 12x + 8 and therefore the stationary points are x=1 and x=-2.
f''(x)= (12x)^2 - 12 and thus f''(-2)=36 (which is positive which means x=-2 is a local minima.
My question is what is the significance of the 36? What does its value represent?
I apologise if anything ive written is unclear. I would like to thank anyone who has any helpful responses.
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