1. S

    Simple Question

    In this photo, this is the process of getting the sinusoidal transfer function. Anyway that doesn't matter. The question is while this procedure, what happened in replacing "sin(wt - 90)" by "(-j) sin(wt)" Thank you in advance.
  2. B

    a simple system with an impossible answer...

    first post here... currently an applied math student attending Stonybrook university. The question seems so simple. But I am unable to find an answer. jack can do 3 chemistry problems and 6 math problems an hour. Jill can do 4 chemistry problems and 7 math problems an hour. How long must...
  3. G

    Where I am doing wrong in this simple interest problem?

    A certain sum of money at certain rate of interest becomes 2100 in 2 years at simple rate of interest and 2250 in 5 years. Find the rate of interest? 2250 corresponds to 5 2100 corresponds to 2 ---------------- (subtracting) 150 corresponds to 3 ?? >>> 2 100 corresponds to 2 then for...
  4. M

    Weird simple question on comparing positive and negative integers

    Hi, I don´t know how to deal with this: When comparing climate impact (contribution of CO2 released to atmosphere) of different types of insulation, how do I compare the positive and negative impact? I want to compare this materials: CORK -59 kg/m2 EPS +23 kg/m2 WOOL +96 kg/m2...
  5. J

    Simple Interest Rate

    John receives an invoice for USD 1000 with payment due within 30 days. The terms of payment allow for a discount of 2.5% if the bill is paid within 7 days. He borrows USD 975 to take advantage of the discount. What is the largest simple interest rate that John would be willing to pay the loan?
  6. G

    Clarify three doubts in simple interest problem.

    A sum of Rs 400 amounts to Rs 480 in 4 years. What will it amount to if the rate of interest is increased by 2%? 400*8/100 = 32 480 + 32 = 512. What is 480? Is it SI or amount? How 8/100 came? What is 512? Is it SI or amount?
  7. B

    How to solve this simple Laplace integral?

    Check this Image. I tried to post it as an image but it takes the entire space of the post... It seems I have forgotten a lot about solving integrals... But I really need to remember quickly how to solve this kind of fractional integrals since I haven't memorized the Laplace "trick" formulas...
  8. Z

    Please explain to me in simple terms what these circle intersections are all about.

    So, say you got 4 circles intersecting this way: Now, I am looking for two things: A proof that each part of the circle which is in an intersection is 1/4 the size of the whole circle's circumference The exact area of the non-shaded region. Now, in my search for finding the answer to...
  9. Violex

    Simple Long division issue is stressing me out.

    Hi All :) I'm reading a book I physically own and I'm doing some Long Division from it. I'm trying to work out: a Double figure Divisor with a 4 figure Dividend. 16 / 4496. So I divide 16 into 44, giving me 2, and a remainder. I drop down and input 32, 44 Subtract 32, gives me 12 and I...
  10. C

    Simple question

    Hello, I'm no mathematician, nor am I any good at math, but I somehow came across this odd set of equations that seem to always work out, with an exception. I was just messing around on my calculator, when the following equations seemed to work themselves out to me. IF a*b=c THEN c/sqrt...
  11. B

    Problem with a simple integration!

    Things I know: \delta ( \tau -1 ) = 1, \tau=1 else \delta ( \tau -1 ) = 0, \tau \neq 1 and \int \delta (\tau -1) = u(\tau -1) where u ( \tau -1 ) = 1, \tau>1 else u ( \tau -1 ) = 0, \tau<1 Integrate to Solve: e^{-2t} \int_{1}^{t}e^{\tau} + e^{2...
  12. H

    A simple answer

    Am I allowed to make a new thread in maths where I believe I have already solved the answer to the question but seek confirmation and things I can add to the solving step?
  13. C

    Complex polynomials with simple roots problem

    What are all the monic polynomials P(X) ∈ C [X], with simple roots such that P(X^n) = ±P(X) P(ζ*X) P (ζ^2*X) …P (ζ^(n-1)*X), where ζ is a primitive n-th root of unity?
  14. B

    I can't calculate a simple infinity integra!!!

    x(t) = \begin{cases} 1 \quad ,0 \leq t \leq 1 \\ 0 \quad ,else \end{cases} The book says to calculate the integral below which must be 1, but I find infinity. \lim_{T \to \infty} \int_{-T}^{T} |x(t)|^2 \cdot dt = 1 My calculation \lim_{T \to \infty} \int_{-T}^{T} |x(t)2|^2 \cdot dt =...
  15. B

    A simple Proof by the Easy Or Hard Way?

    Given the equations below prove that v^2 = v_0^2 + 2a(x-x_0) 1) v = v_0 + at 2) x-x_0 = v_ot + \frac{1}{2}at^2 Easy Solution: v = v_0 + at \Leftrightarrow t = \frac{v-v_0}{a} Substituting t into equation 2 \Delta{x} = v_0\frac{v-v_0}{a} +...
  16. H

    Simple Harmonic Motion

    Guys please how do i go about this questions? 1.Alex goes to bed at 7:00pm everyday.Is it an example of periodic motion?If yes,what is the time period?If no,why? 2.A particle executing S.H.M comes to rest at the extreme position.Is the resultant force on the particle zero at these position...
  17. I

    Simple sequence

    Find n-th term or function f(n) that defines the sequence 2,2,0,0,0,....\; \; (infinite zeros after second term)
  18. H

    Help me on simple algebra

    How can we equate the expression a+x(b-a)=b+a-y(a+b) in such a way that we will obtain 1-x=1-y HELP ME
  19. K

    simple inequality problem

    x and y integer -5<x<4 -8<y<1 what is the maximum value of 2x-3y? when i multiply first eqn by 2 and second by -3 and the add them up i get -13<2x-3y<32 which makes the answer 31 but that is not even given in answer choices and the answer they say should be 27 . please help
  20. C

    Let G be a simple graph with c connected components

    I need help solving the following problem: Let G be a simple graph with c connected components, which have a1, . . . , ak vertices, respectively. Determine the number of ways to add c − 1 edges to G to form a connected graph, in terms of the numbers ai .