1. K

    Elementary Question: Explain a step in a proof.

    I'm reading the paper "On Periodicity of Trigonometric Functions and Connections with Elementary Number Theoretic Ideas," which was written for an audience of Australian high-school teachers. It begins with analysis of a simple problem: "What is the period of the function f(x) = sin(2x+a), where...
  2. D

    Can someone explain Rational, Irrational and Imaginary zeros to me?

    Every time I search for the definition online, they always have really complex words that makes it even more confusing, I was wondering if someone can tell me the definitions but make it simpler. Thanks. Also this would be irrational right? -2 plus or minus square root of 5? How do you know...
  3. A

    Can you explain my method?

    I've been looking at the problemu_y + (2x+u)u_x - (x+2u)=0 \qquad u(x,0)=1-x I'm a little hazy on the exact justification of the method, but essentially I think I assumed that there might be a solution of the form u(x,y)=\phi\big(x-(2x+u)y\big) where u(x,0)=\phi(x) = 1-x. I then wrote{\mathrm...
  4. tim541

    Can someone explain me the term 6.5/1.2?

    From where it comes from?
  5. T

    Trig Word Problem - Please Explain

    Hi, I have this word problem which I don't quite understand how to find the answer for, so if you could be thorough in answering that would be great! When the Sun is at an angle of elevation x, a tree with a height 12 m casts a shadow of length s, in metres. a) Show that the length of the...
  6. T

    Could someone explain me how to solve this integration problem thanks

    I really struggled to this question so if someone know it please help this question 15 and 12 from core 2 Thanks Given the picture below (Rofl) https://www.dropbox.com/s/lqb4l3kmyk5dhr1/20150719_002739%5B1%5D.jpg?dl=0 https://www.dropbox.com/s/1ill9kjq2kzmtqr/20150719_002759%5B1%5D.jpg?dl=0...
  7. Z

    please explain this cancelation

    .............when I do ex. problems I get the same answer, the wrong answer: 7(would be zero)+h^2 or 7h + h......if h^2 was in the demonstrator I would understand, but how are they canceling two h's......lol please elaborate.(Headbang)
  8. T

    Explain why there are 2 ^ 19 different compositions of 20

    Hello, I would need some help to clarify the solution of this. Aka using rings ("O") and "|" to explain why there are 219 (524288) different compositions of the number 20. I also need to know how many of these compositions have only even terms. For example 6+2+12 ( OOOOOO|OO|OOOOOOOOOOOO) is a...
  9. H

    Please explain.

    Definition: The altitude from the vertex of the right triangle to the hypotenuse is the geometric mean of the segments into which the hypotenuse is divided. So, from the attached image: 1. DB^2 = AD*DC 2. CB^2 = CA*CD 3. AB^2 = AD*AC I can agree with 1. DB^2 = AD*DC from the definition AND...
  10. D

    Can someone explain this? (Speed=Distance*Time)

    I'm in the process of joining the Police service and as a part of the entrance I'm working on my maths and seem to have hit a wall with speed / distance x time. Can't find much on the internet regarding this. Baring in mind I've been out of school for some time now, I've had to relearn...
  11. N

    explain what rule of inference are used to obtain each conclusion from premises?

    (b) "if i eat spicy food,then i have strange dreams". "I have strange dreams if there is a thunder while i sleep". "I did not have strange dreams". p= i eat spicy food. q = i have strange dreams. r= there is a thunder while i sleep. p -> q. r -> q -q. ----- -p (or) q. -r (or) q -q Can...
  12. W

    Can someone explain this simplification process to me in greater detail?

    Hi forum. This will be my first post. Glad to be here. This is from a calculus problem. This is the first derivative of the function. The algebra part is killing me though. Can someone explain how this is simplified from left to right? How do they achieve the end result? I suspect they are...
  13. J

    always true or sometimes false, explain

    I have these that ask if always true or sometimes false a) All vectors of the form (a, 1, −a) form a subspace of $\mathbb{R^3}$ I said false because it doesn't contain the zero vector b) All vectors of the form (a, 0, −a) form a subspace of $\mathbb{R^3}$ true because closed...
  14. H

    Explain Why a Root is Close to...

    Show that Use this to explain why is close to, but slightly less than, 10.05. ~ I know why the first part equals the other, but what relevance has that to the explanation?
  15. maxpancho

    explain why 1/x has no loc max or loc min

    I know this is pretty basic, $$ \frac{d}{dx} (1/x)=-x^{-2}\\ -x^{-2}=0 $$ but what do we say at this point, rigorously?
  16. R

    Can you explain how I solve this? ('general terms')

    We are given this problem and I am having trouble with some of it, specifically 'writing the general term '' I really don't understand wha most of the questions are even asking me. a) next 3 terms are (5,24) (6, 35) (7,48) b) is simple as plotting those numbers in a table c) I believe...
  17. H

    Please explain sine

    There is a formula: Area of segment of circle = r^2 (pi*theta/360) - (sin theta/2), where theta is a measure of corresponding arc in degrees. Could you please explain how they introduce sine in this formula? why not cosine?
  18. sakonpure6

    Explain a graph please :)!

    I know this might seem very elementary, but I am having trouble understanding why \frac{|x|}{x} looks like this https://www.desmos.com/calculator/lzcondzabk To my understanding the Xs should cancel out and we should get a new equation disregarding the original. What am I missing here? Thank you!
  19. M

    Explain how these proofs work

    Hi all, We have made it to function proofs in my class. I really have a hard time understanding proofs at all. Can someone explain to me how these couple examples: These are 2 of many questions from my homework, and I have no idea how to do them. Let f : Z x Z --> Z state whether the...
  20. B

    Please explain why limits exist or not-DO NOT use ANY adv method to solve it

    Hi, I 've just started Pre-calculus this semester, wonder-can anyone explain to me why the following limits exist or not? Please DO NOT use ANY advanced mathematical methods to solve it. No.1 {\lim _{n \to \infty} \(-1)^n} The answer is Does not exist. Please explain why. No.2 {\lim _{n...