Recent content by romsek

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    MHB Winning Tennis with Probability 0.3 and 0.7

    Have you worked out the states and the state transition probability matrix? I see the states as Deuce, Ad-In, Ad-Out, Game with Game being an absorbing state.
  2. R

    MHB Find Limit of $\displaystyle\frac{\sec x +3}{7x-\tan y}$ at (0,$\dfrac{\pi}{4}$)

    No. $$(x,y) \to \left [0, \dfrac \pi 4\right]$$ is the same as $$x \to 0,~y \to \dfrac \pi 4$$ i.e the limit at the point $$\left(0,~ \dfrac \pi 4\right)$$ If you can plug them in and get a value, great, that's your limit. But generally plugging the values in will result in 0 in the...
  3. R

    MHB Show that the codeword a cannot be a valid codeword.

    what's the Hamming distance of the (7,4) code? (hint: it's 3) Can a valid codeword exist at a Hamming distance of 2 bits in a code with a Hamming distance of 3?
  4. R

    MHB How can I solve the problem of $e^x-\ln{x}=4$ without a calculator?

    Newton's method solves this readily enough.
  5. R

    MHB This is sampling distribution can you help me with this problem

    maybe they just need to move some goats! :ROFLMAO:
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    MHB Matrix Transforms: nxm, n->m, m->n, n+m->n/m

    Matrix multiplication (note that a vector is just an m x 1 matrix) (n x m) X (m x k) => (n x k) See if you can figure it out now.
  7. R

    MHB Why Is My Solution 9x+-11 Incorrect for the Algebra Problem -6(x+2)+10+3(x-3)?

    you can combine the numbers, $$-12+10-9$$ as well
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    MHB Vowel-Consonant Arrangements and Non-Adjacent Vowels

    You are omitting all the cases where two vowels are adjacent but the others are not, or where two pairs of vowels are adjacent but separated by a consonant.
  9. R

    MHB Vowel-Consonant Arrangements and Non-Adjacent Vowels

    2) is simple. Just look at how many valid digit choices you have for each digit of a 3 digit number. Note that 0 is not included as a possible digit and so we can't use the number 100 anyway so we don't have to worry that we don't use every 3 digit number. 3) Use stars and bars 4) Is a bit...
  10. R

    MHB Vowel-Consonant Arrangements and Non-Adjacent Vowels

    There are 2 sets of letter positions vowels can be placed in such that they are never adjacent. These are letters $$(1,3,5,7)$$, and letters $$(2,4,6,8)$$. Within these slots there would be $$4!=24$$ arrangements of the 4 vowels however there are 2 of the letter "A". Thus we have...
  11. R

    MHB B.2.2.2 solve DE ....separate variables

    $$y^\prime = \dfrac{dy}{dx}$$ so just "multiply" both sides by $$dx$$ Have you read on how to solve separable diff eqs?
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    MHB B.2.2.2 solve DE ....separate variables

    $$y^\prime = \dfrac{x^2}{y(1+x^3)}\\~\\ y dy = \dfrac{x^2}{1+x^3}dx\\~\\ \dfrac 1 2 y^2 = \dfrac{1}{3} \log \left(x^3+1\right) + C\\~\\ y^2 = \dfrac 2 3 \log(x^3+1) + C~\text{(note the constant absorbs multiplication by other constants)}\\~\\ y = \pm \left(\dfrac 2 3 \log(x^3+1) +...
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    MHB Combination/probability question (High School level)

    It's a bit difficult to cite any approach as "best" given the variety of problems that exist but generally separating the cases helps ensure you won't multiply count specific situations.
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    MHB Combination/probability question (High School level)

    With your method groups with 3 girls get counted 3 times each rather than once each.
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    MHB B.2.2.16 IVP of \dfrac{x(x^2+1)}{4y^3}, y(0)=-\dfrac{1}{\sqrt{2}}

    We easily obtain that $$\dfrac{dy}{dx} = \dfrac{x(x^2+1)}{4y^3}\\ 4 y^3 dy = (x^3 + x) dx\\ y^4 = \dfrac 1 4 \left(x^4 + 2 x^2 + C\right)\\~\\ \text{It's easiest to evaluate the constant here}\\ (y(0))^4 = \dfrac 1 4 C = \left(-\dfrac{1}{\sqrt{2}}\right)^4 = \dfrac 1 4 \Rightarrow C = 1\\...