Search results

  1. stapel

    Number of days ate 3? You begin with 28 sweets. Each day, you consume 2 or 3 sweets. In 12 days, you finish all 28.

    If you ate only two each day, how many would you have eaten over the course of the twelve days? How many sweets would be left over? So how many days must you have eaten a third sweet?
  2. stapel

    indexing ... how to solve (5th-rt(243) * sqrt(64^3))/(27^(2/3) * 512^(-2/3))

    Has your class not covered exponents and radicals yet, so you need an explanation of the topic? If so, there are loads of lessons available online, such as in this listing. Please study at least two lessons from the listing, and then attempt the exercise. If you get stuck, you can then reply...
  3. stapel

    Please solve 😩 9 ÷ 3(1 + 2)

    Yes, after an application of relevant rules, there can be only one answer. But, because the posted expression is ambiguous, we can't be sure which rules are being used. Therefore, people can arrive at two different answers, depending upon which rule(s) they have assumed were to be applied. This...
  4. stapel

    Straight line problem: line through (-5,-4) meets x+3y+2=0, 2x+y+4=0, x-y-5=0 at B,C,D respectively. If (15/AB)^2+(10/AC)^2=(6/AD)^2, find line's eqn.

    What are your thoughts? What have you tried? How far have you gotten? What recent results/rules/theorems have been covered in class? ("Read Before Posting") Please be complete. Thank you!
  5. stapel

    Is there a formula that predicts the amount of digits of the multiplication of two very large numbers?

    Think about the vertical multiplications you've done by hand. For each digit in the lower number, you'd get a row below that you would then add. Each row's start was shifted one place to the left. Thinking of those rows, you would have (as many digits as the top number, or maybe one more because...
  6. stapel

    Why does the answer I get is always -2/3 when the solution says its -3

    It's not that it's a totally different question. It's that we're used to thinking in terms of positive infinity, and we forget that, just because there is no "minus" sign on the exponent, doesn't mean that it isn't negative. It's a human failing. But yes, you *will* need to be careful because...
  7. stapel

    Why does the answer I get is always -2/3 when the solution says its -3

    You're thinking in terms of x trending toward *positive* infinity. But the limit is for *negative* infinity. When you're on the negative side of the x-axis, e^{2x} is going to get very small, because the 2 is positive and the x is getting strongly negative, so the base is being raised to a...
  8. stapel

    dividing a load of work correctly

    Does this mean that they overlap for at least 25% of the time? I don't know. What algorithm are you supposed to apply? What are the rules?
  9. stapel

    f(x) = sqrt( (e^x) - 1 ): find the domain, find 1st and 2nd derivatives, and test for concavity

    I get the same result. Now try simplifying the second half of the expression by breaking the one fraction into two: \qquad \dfrac{1}{2}\left(\dfrac{e^x\, sqrt{e^x - 1\,}}{e^x - 1} - \dfrac{e^x \cdot e^x}{2\sqrt{e^x - 1\,}(e^x - 1)}\right) \qquad \dfrac{1}{2}\left(\dfrac{2e^x\, \sqrt{e^x -...
  10. stapel

    calculus problem: For which non-negative values of a does the function y=(x^2+3x)/x+a have a clear discontinuity point?

    What you have posted means the following: \qquad y = \dfrac{x^2 + 3x}{x} + a Was this what you meant? Because, if so, I can understand your confusion; the value of a has nothing to do with any discontinuity of the function. If not, what *did* you mean? When you reply, please clarify at what...
  11. stapel

    help please

    You've posted a picture containing four named shapes, various parts of which are shaded, and given us a cryptic reference to whatever were the original instructions. However, we need further information, starting with what you mean by "operations" that you are supposed to "write" (as opposed to...
  12. stapel

    Linear Algebra Vectors (Find point P in R3 such that A,B,C and P form a rhombus)

    What are your thoughts? What have you tried? How far have you gotten? ("Read Before Posting") Please be complete, so the helpers can see where things are going sideways. Thank you!
  13. stapel

    I need help: Suppose that f is a function with f(110) = 55 and f'(110) = 4. Estimate f(113).

    What are your thoughts? What have you tried? Where are you getting stuck? ("Read Before Posting") Please be complete, so that we can see where things are going sideways. Thank you!
  14. stapel

    Can someone check my working on this algebra? (alpha) + (beta) = -5/2, (alpha)(beta) = -5, (alpha)^2 + (beta)^2 = 65/4, (alpha)^3 + (beta)^3 = -425/8

    Thread moved. Would it be correct to assume that the first four lines are the "givens", and that the starred line indicates the beginnings of computations based on those givens? So the problem statement was along the lines of the following? \qquad \textrm{Given that } \alpha + \beta =...
  15. stapel

    Gaussian elimination with augmented matrix

    Is there a typo in the first row? Shouldn't it be x_1 + 2x_2 - x_3 = 6? You can either operate *with* a row or else *on* a row, but you can't do both. And it appears that what you did was operate *on* the row, by multiplying by -\frac{1}{5}, which is fine. I'm not sure what you did here, but...
  16. stapel

    5th grade math question: 5 packages. 12 people. How much does each person get?

    If you're not sure of your answer, check it. If each child gets \frac{5}{12} of a package, then the twelve children will, in total, get 12\left(\frac{5}{12}\right) packages, which is all 5 [packages. As for the "how" for the "proper" (that is, the expected) way to arrive at the answer, I cannot...
  17. stapel

    Is it possible to solve for any variable in this system of equations? (All variables must be > 0; no variable can be +- 10,000 from another)

    You have three equations in six unknowns. Kinda by definition, you cannot solve for unique numerical values.
  18. stapel

    Function: If (fog)(x)=(sin squar x) ^ 2 and (gof)(x)=|sinx|, find f(x) and g(x)

    What are your thoughts? What have you tried? How far have you gotten? ("Read Before Posting") When you reply, please include a clarification of the expression for (f \circ g)(x). In particular, it looks as though you are squaring the sine twice: \left(\sin^2(x)\right)^2. Is this correct? Thank...
  19. stapel

    Real analysis: Given A= {b∈ (1, 7) : b ∈ Q^c} how to find its interior, exterior, boundary, isolated, limit and closure.

    Please reply with a clear listing of your thoughts and efforts so far, so the helpers can see where you are getting stuck. Thank you!
Top