1. A

    Simple trig question giving me trouble

    I was tutoring somebody in high school this morning and we were going over the use of graphing calculators (he gets to use them for tests and finals), and the chapter about graphing functions in his pre-cal textbook came up that gave me some trouble. I tried working at it for a bit, but couldn't...
  2. R

    the other factors whether it’s giving up smoking

    That as a public health activist that I do understand signs which dodgy but there was a meta review which means that was a reviews lots of different scientific reviews were brought together in the study and all the slide shows is that if we want to sustain life and improve health we should be...
  3. K

    Calculus word problem is giving me trouble

    Hi, I've been given this problem: imgur: the simple image sharer and I am honestly not sure where to start. Any help is appreciated. Thanks!
  4. Q

    Simplifying and giving answers in cartesian form

    Hi there i have a question to ask The following must be simplify and must be answered in cartesian form, present your answer on an argand diagram. Im not too sure how to do these could someone explain it please? thank you :) Question (a) (4+5j)(4+5j) Question (b) (-5-2j)(5+2j)
  5. L

    Disc method and shell method giving different solutions

    I have the function f(x)=x2 I am to give the volume of the shape when this function is spun 360 degrees around the x axis by using the disc method, and the shell method, from x=1 and x=3. When I work out the disc method, I get (242pi)/5. But when I use the shell method, I get (232pi)/5. I have...
  6. Paze

    Combinations giving me a headache

    I've watched several videos and read several articles but nothing seems to help. I can't for the life of me get a firm grasp of combinations. I have a very easy time realizing permutations. It's logical, I have 3 spots and 5 people to fill it. In the first spot I have 5, in the second I have 4...
  7. L

    Equation with negative variable exponent giving me trouble

    How would this be worked out if there was a negative exponent of x? Lets say: 3x - 4 * 3-x > 0 It seems as if I put those into logs, it would turn into x log 3 + (-x)log 3 > log 4 Would that be the correct way of doing it? Because that looks like the two x log 3 groups should cancel...
  8. A

    autocorrelation function is not giving 1 at zero lag can sumone tell me whats wrong

    function [Rxx]=autom(x) % [Rxx]=autom(x) N=length(x); Rxx=zeros(1,N); for m=1: N+1 for n=1: N-m+1 Rxx(m)=Rxx(m)+x(n)*x(n+m-1); end; end; x=[8.121132 8.580819 8.274361 6.2823853 5.209783 2.6048915 4.4436383 4.4436383 12.411542 5.209783 0.45968673 2.4516625 -2.9113493 -0.15322891 -0.91937345...
  9. M

    Giving an Exact Solution to a Logarithm

    Subject are exactly what the instructions are and I have no problem doing logarithms until I came upon this problem. Teacher didn't really give any examples like this one and I am totally lost. I have no idea how to write that exactly as I see it Any help is GREATLY appreciated thank you!
  10. J

    Solve giving all solutions in the interval 0 ≤ x ≤ 180

    I have to solve sec x = 4 − 2 tan^2 x, giving all solutions in the interval 0 ≤ x ≤ 180 , i have no idea where to start..... so far i changed the tan into sec^2-1, but i still cannot solve, i think they want me to use binomial expansion (Headbang)
  11. S

    integration by trig substitution giving me different, equivalent answers, as calcula?

    Hi. Using trig sub to get integrals, I keep getting different but possibly equivalent answers as in book, and on calculator. For example, integral(5/sqrt(25x^2-9),x) By trig sub, I get: ln|5x/3+(5sqrt(x^2-9/25)/3|+c Calculator gets: ln(sqrt(25x^2-9)+5x) Wolfram integrator gets...
  12. D

    Calculator giving me wrong answer

    Hello, I am having issues with following along with the example problems for my homework. When I try to evaluate with my calculator, the answer is different from what the answer in the example states. I need to plug in t=.5 into the formula s(t)=29sin2t The example states: s(.5) =...
  13. N

    Giving answers to the nearest degree, find in the interval 0<x<360

    Giving answers to the nearest degree, find in the interval 0<x<360 all the solutions of: 10 sin(x+26) cos(x+26)=1 rather than the answer, id like to know the solution ie how to work it out. i have my mock exam tomorrow, please answer me asap please. thanks, neilofbodom
  14. A

    finding the "end points" of an orthogonal line giving the lenght

    First of all sorry if am posting on the wrong sub forum or the title is a little misleading.. Am working on a software right now, and am really embarrassed that I dont remember the basic mathematic to solve this problem. this is the thing, for any given line (lets say L1) I need to create two...
  15. S

    Nonzero determinants giving an inconsistent system with no solution?

    Hello, For a 3 by 2 matrix, which is not square, how does one determine values that make the system inconsistent, since by definition, we cannot find the determinant of such a non-square system? If we augment the matrix by including the solution vectors, the system becomes a 3x3 matrix, at...
  16. Y

    Find k of f(x) giving the following criteria

    f(x)=x^3-kx, where k can be any number. Find the values of k such that f has no critical numbers, one critical number, and two critical numbers. If anyone could help me find one of those, I'll see if I can figure out the rest. I'm assuming so far we set the derivative to 0, but I'm not...
  17. U

    Partial derivative, is the answer Im giving right?

    Well, it looks simple, but I'm not sure If the answer I'm giving is right. The function is: f(x,y)=\sin|y| And it asks for the partial derivatives, so: \displaystyle\frac{\partial f}{\partial x}=0 And \displaystyle\frac{\partial f}{\partial y}=\begin{Bmatrix}{ \cos|y|}&\mbox{ if }&...
  18. P

    PDE by Fourier soltion giving zero coeffiecant

    PDE by Fourier solution giving zero coeffiecant Hi all, I am working through a PDE and get through to the general solution, but get a seemingly zero Fourier coefficient. \frac {\partial u}{\partial t} = \frac {\partial^2 u}{\partial x^2} Using seperable variables method and...
  19. D

    Impossible number grids giving me grey hairs!

    Hi guys. A challenge for you all: This is the third forum I'm trying, and thus far the squares below remain unsolved. It is my hope that this forum will change that! Attached are two number grids. One is a 10X10 and and contains numbers 0-9. The other is a 12X12 and contains number 1-12. The...
  20. H

    Summation of a series giving logarithm

    I need to prove that \sum_{i=1}^{\infty}\sum_{j=1}^{i-1}\frac{(-1)^i}{i j}=\frac{1}{2}\ln ^2 2. The obvious way would be to compare with the series on the r.h.s. which is \frac{1}{2}\sum_{i=1}^{\infty}\sum_{j=1}^{\infty}\frac{(-1)^{(i+j)}}{i j}, but I just can't show that they're the same. Any...