Mathematics - 7 December 2007

complex numbers are all abstracts,,not even used to count things,,lol,,
calculus i don't know what do u do differentiating and integrating variables,,

what are their profitable uses??

2007-12-07 00:52:47 · 3 answers · asked by gunkedar 2

I recently got this question in a coursework:

Find the maximum value of f(x) = 4x^2 - x^4 + 4.
For what value(s) of x does this occur.
That was the full question, it didn't state any desired method to use.

So I got: dy/dx = 8x - 4x^3

worked out that when dy/dx = 0, x=0 or +/- sqrt(2)

then I got: d^2y/dx^2 = 8 - 12x^2

so when x = 0, d^2y/dx^2 = +8, ie a minimum.

when x = +/-sqrt(2), d^2y/dx^2 = -16, ie maximum.

so I put x = +/- sqrt(2) back into the original equation to get 8.

My final answer was the maximum is 8, and this occurs when x = +/- sqrt(2).

But I only got 2 out of 4 marks. He/she (I'm not sure who marked it) put a note next to my second derivative saying that I have to evaluate them. I don't know what this means, I have evaluated the answer and surely I don't have to evaluate f(0) if I know it's a minimum.

What are your thoughts?

2007-12-07 00:17:12 · 5 answers · asked by eazylee369 4

Hey can anyone help me out with this question please??

Use five terms in a power series to estimate:
Integral 0 to 0.2 of (arctan(t^(2)))/(t) dt
(the arctan is in the top of the fraction not preceding it)

Please help!!

2007-12-07 00:15:27 · 2 answers · asked by Anonymous

okay so im doing a math project and i am supposed to be explaning a simple math problem to the teacher. i just need some help on finding a way to explain it clearly..
[2x+1]=5

2x+1=5 2x+1= -5
-1 -1 -1 -1

2x=4 2x=-6

\2 \2

X= 2 X= -3



Check:
2(2) +1=5 2(-3) +1=5
4+1= 5 -6+1=-5
5 = 5 -5 = -5

how do i explain each step clearly?

2007-12-07 00:12:42 · 4 answers · asked by Hannah Y 1

I can up with -11/7. is that right

2007-12-07 00:04:33 · 5 answers · asked by peaches 1