221 reputation
11
bio website
location New York
age
visits member for 1 year, 9 months
seen Apr 11 at 0:02

I am a retired Electrical Engineer with 42 years of experience. I have BSEE and MSEE degrees.


Feb
18
comment How to solve $5^{n+2} - 5^{n-3} = -2500$
Your solution is not correct. log(-x) does not equal -log(x).
Aug
13
awarded  Yearling
Aug
12
answered What is power of number like (power of 2, power of 10)? and how to calculate power of number.
Jun
20
comment Given $d(x) = \sqrt x + 3$ and $g(x) = 3\sqrt x - 2$, find $k(x) = 4\left(\frac{g}{d}\right)(x)$.
The questioner's answer is not correct since he has a 14 instead of 24.
Jun
20
answered Given: $f(x)=5/(x+4)$ and $g(x)= -1/(7-x),$ find $h(x)=(fg)(-3)?$
Jun
20
answered What does it mean “Range”?
Jun
17
comment Two students clean 5 rooms in 4 hours. How long do 40 students need for 40 rooms?
You flipped the numbers: they both clean 5/4 rooms per hour and one then cleans 5/8 rooms per hour. Forty students can thus clean 200/8 rooms per hour or 25 rooms per hour. To clean 40 rooms then takes 40/25 or 1.6 hours, in agreement with all of the above answers.
Dec
1
answered What's wrong with my sum? ($S=1^2+2^2+3^2+\cdots+10000$)
Nov
29
comment What's wrong with my Mac Grapher?
I used by trusty TI-83 calculator and it graphed all of the functions over the whole domain with no problems.
Oct
29
comment Which filter is the most suitable if I know points with zero noise amplitude
I think some more information is needed. First, you seem to have n points consisting of data plus additive noise. Somehow you know that the additive noise is zero for some of the points. However you are using the same index n for both of these series. I think you need to redefine the index of the points with zero noise, e.g. m where, presumably m<n. As for a filter, a better description of the input and expected output of this filter is needed.
Oct
28
comment Very very simple probability question
Your solution is correct but this is not a probability question as it is completely deterministic. No probability is involved.
Oct
9
answered How do I find the solution for these exponential equations?
Oct
3
comment Is this a valid proof of the Goldbach's theorem?
I don't see where you have proved anything. Your statement at the end of the 3rd paragraph (any prime number cannot be an even number) follows directly from the definition of a prime number. You have not shown anything relating to Goldbach's conjecture.
Sep
27
answered Find the solution of each of the following initial value problems
Sep
25
comment Why is $i! = 0.498015668 - 0.154949828i$?
the "z" should be a "t" in the last formula.
Sep
3
awarded  Teacher
Jun
28
comment Section of a circle
In your example, the height to the chord is equal to the radius. Therefore the chord becomes a diameter and the angle subtended by a diameter is 180 degrees.
Jun
28
answered Section of a circle