All Answers

+6252

the only real difference in showing these things in 1D vs ND is what is used as a measure of length.

In 1D it's absolute value

in 2D it's the vector length, i.e. ||(x,y)|| < delta

using the usual Euclidean metric ||(x,y)|| = sqrt(x ² + y ²)

so whenever, in your epsilon/delta proof, you need to show that some length is smaller than some number you use this metric rather than just absolute value.

When you go to ND the metric is the same you just include the rest of the vector terms.

See if you can work it now.

RomFeb 5, 2014

+6252

Quote:
x = 9.5y2 - 242.5y + 1,500

what's the question?

RomFeb 5, 2014

+6252

Quote:
x ³ · x -4 · x

do you mean

x ³ * (x-4) * x ?

or

x ³*x - 4*x ?

RomFeb 5, 2014

+72

Cody said b/-3 +12= 23 Solve for b.
b/-3+12=23
multiply althrough by -3 gives:
b - 36 = -69
make b the subject
=> b = -69 + 36
=> b = -33.

Princess Sophie EFeb 5, 2014

+6252

For your early engineering and EE classes a few things you'll want to have down cold

a) trigonometry - I assume you'll need to take statics, dynamics, physics I and II, all these will make very heavy use of trig

b) basic linear algebra - You need to know how to manipulate matrices very well. You should be able to quickly find the inverse of a 3x3 matrix using row reduction.

c) if you have any questions about the exponential function get them worked out because it is the key function used in EE. You should understand the exponential of a complex argument as well.

d) speaking of complex numbers you'll need a solid understanding of what they are and how to manipulate them.

e) it goes w/o saying you should be good with basic differentiation and integration.

f) you'll eventually need a solid understanding of sequences and series

g) eventually you'll need a solid understanding of probability but that will come a bit later and may not come at all depending on which area you specialize in.

h) eventually you'll need a solid understanding of basic differential equations and boundary conditions.

this ought to keep you busy for a while

RomFeb 5, 2014

+6252

Quote:
-4(4-x)^2<8-(4-2x)^2

(4-x) ² = 16 - 8x + x ²

(4-2x) ² = 16 - 16x + 4x ²

substituting these in

-4 (16 - 8x + x ²) < 8 - (16 - 16x + 4x ²)

multiply everything out

-64 + 32x - 4x ² < 8 - 16 + 16x - 4x ² = -8 + 16x - 4x ²

combine all the like terms

-56 + 16x < 0

16x < 56

x < 56/16 = 7/2

RomFeb 5, 2014

YOU IS GOIN TO NEED IT IT EVERYTHING YOU DO...................

GuestFeb 5, 2014

+2354

Melody:
I just stumbled on this you tube clip.
I thought it was quite good. That is because it is basically the way I teach it (I have looked at many methods in the past and i like this one)
My only criticism of this clip is that he keeps waving his pen about and it is a distraction.
http://www.youtube.com/watch?v=ZQ-NRsWhOGI
--------------------------------------------------------------------------------------------------------------------------------------------------------
I was thinking that we could start a thread, where the url's of the resources that we like, are added.
Maybe they could be posted individually when first introduced but then assigned to a thread bank of resources.
Does this sound like something people would want to do?
Or is it easier just to go find them each time on the web?
Obviously there are a lot of resources out there. Some are good, some are really not.
also, we won't all like the same ones.

I am just looking for some comments/ideas please.
Would anyone, other than me, like to organize something like this. If not, it doesn't matter. I know you are all busy people.
We could even have our own post within the thread that we look after with edits and additions for ourselves. Do you understand what i mean?
Thanks,
Melody.

I think it is a good idea to have a thread where everyone can share his or her recources.
I'd use it to give quicker answers to the similar questions that are asked every day.
People might share recources which are not so useful (could be a man waving a pen through the screen (just kidding )) but we're not obliged to use them in our answers.
Simply watch the recource before your use it in an answer and then it will probably be an excellent idea!
How about this thread?

reinout-gFeb 5, 2014

#68

+2354

Melody:
HARD ONE
2 2 5 7 17 20 and the magic number is 1994

Maybe we could have a little hint ? Please Reinout-g

Hint: 1994/2 = 997

reinout-gFeb 5, 2014

+118725

Thanks reinout-g

MelodyFeb 5, 2014

+2354

Melody:
gutierrez:
three cousins, allan,bob,and charlie,were sitting around watching football on tv. the game was really boring, so they started talking about how old they were. allan (the oldest)noticed that they were all between the ages 11 and 30. bob noticed that the sum of their ages was 70. charlie (the youngest) stated, "gee, if you write the square of each of our ages, all the digits from 1 to 9 will appear exactly once in the digits of the three squares. how old was each person?

I did it entirely by myself.
I used excel just for ease of presentation.
There is only one solution for the squares part.
I did not use the total 70 in any calculation.

Charlie is 19, Bob is 23 and Allen is 28

140204 ABC age puzzle.JPG

I am seriously missing a like button here!
* like *

reinout-gFeb 5, 2014

+2354

AngelIshtar7:
Ranges from 6.57 to 7.93. Write the desired point ± tolerance statement. How do I do this?

Hi Angellshtar,

I assume this question is a subquestion of a bigger exercise.
I believe we might be able to answer your question more accurately if you post the rest of the questions along with this question.
Even though you might already know the answer to those it could help us understand your question.

reinout-gFeb 5, 2014

+118725

bob:
ok got it its 23 ft away

I don't think so Bob.
Your question was a little different from the one in the example

I think that it is

4 * 260 = d * 80

Look back at the page I sent you to and see if you can work out why the questions are a bit different from each other.

Oh and thank you for answering the other person's question.

MelodyFeb 5, 2014

+46

3 into 2629
3 cant go into 2 but can go into 26
you get 8
then 22
you get 7
then you get 19
and you get 6
then you get 1 and it would be 876 and 1/3

bobFeb 5, 2014

+46

ok got it its 23 ft away

bobFeb 5, 2014

+46

you need to find all 2 digit #s with a 3 first

13; 23; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 43; 53; 63; 73; 83; 93
now determine if it is prime or not
13 prime
23 prime
30 not
31 prime
32 not
33 not
34 not
35 not
36 not
37 prime
38 not
39 not
43 prime
53 prime
63 not
73 prime
83 prime
93 not
8 2 digit #s with a 3 are prime

bobFeb 5, 2014

+118725

bob:
An object that is 260 lbs and 4 ft away from the fulcrum is exactly balance with a ballerina that is 80 lbs. how far away is the ballerina from the fulcrum

Hi Bob,
Why don't you try and work it out yourself?
This page will help I think.
http://www.onlinemathlearning.com/lever-problems.html

MelodyFeb 5, 2014

+118725