First Year Mathematics A (Differentiation & Linear Algebra) (2 Viewers)

[InteGrand]

Re: MATH1131 help thread

How do I do this in MAPLE?

I understand you use sum(); but what do you do with the n^5/2 on the left??

The expression in the limit is not a sum, but rather a product. This is because that symbol is capital Pi (), which is used for products. The symbol for summation is a capital Sigma ().

 

[Flop21]

Re: MATH1131 help thread

The expression in the limit is not a sum, but rather a product. This is because that symbol is capital Pi (), which is used for products. The symbol for summation is a capital Sigma ().

yeah sorry I actually meant product(); originally.

 

[Flop21]

Re: MATH1131 help thread

bump someone help me with these MAPLE questions pls

 

[Red_of_Head]

Re: MATH1131 help thread

How do I do this in MAPLE?

I understand you use sum(); but what do you do with the n^5/2 on the left??

Try

limit(n^(5/2)*(product(2*k/(2*k+5), k = 1 .. n)), n = infinity)

 

[Red_of_Head]

Re: MATH1131 help thread

How do I solve this in MAPLE?

My incorrect attempt was to go... s:= [solve(expression)] then allvalues(s[1]); to find first root... same for all other roots, then evalf(result, 10); on each root.

Anyone know the steps to the correct way to get right answers?

Close, but maple can calculate all roots for a polynomial like that at once, so you don't need to specify an interval. Your first part, solve z for p(z)=0 is correct. This doesn't give numerical values though, so you need to use evalf.

 

[Flop21]

Re: MATH1131 help thread

Thanks!

How do I do this one?

 

[Red_of_Head]

Re: MATH1131 help thread

Thanks!

How do I do this one?

To find roots p(z) must =0. So the command looks like:

solve(p(z)=0,z);

That will give you a list of roots, but they're not numerical values. To find those, we use the evalf command. Your input should look like:

evalf(solve(p(z)=0,z));

 

[Paradoxica]

Re: MATH1131 help thread

Thanks!

How do I do this one?

You could solve for the roots and then find the principal arguments by somehow extracting the imaginary part and the real parts.

Then take the inverse tangent, of the imaginary part divided by the real part

 

[Flop21]

Re: MATH1131 help thread

To find roots p(z) must =0. So the command looks like:

solve(p(z)=0,z);

That will give you a list of roots, but they're not numerical values. To find those, we use the evalf command. Your input should look like:

evalf(solve(p(z)=0,z));

"principal argument" though, so where do I use argument();?

 

[Red_of_Head]

Re: MATH1131 help thread

"principal argument" though, so where do I use argument();?

Sorry about that Flop, misread the question.

So if you follow what I mentioned before, you should end up with a list of complex numbers (let's say [C1,C2,C3,C4,C5]). To find the argument of these complex numbers, we can apply the argument command to each one, then end up with arguments for each root. Then your answer will be the largest value.

OR (much more easily):

max(argument~([C1,C2,C3,C4,C5]);

 

[Flop21]

Re: MATH1131 help thread

Sorry about that Flop, misread the question.

So if you follow what I mentioned before, you should end up with a list of complex numbers (let's say [C1,C2,C3,C4,C5]). To find the argument of these complex numbers, we can apply the argument command to each one, then end up with arguments for each root. Then your answer will be the largest value.

OR (much more easily):

max(argument~([C1,C2,C3,C4,C5]);

Wow I didn't know about that "~" or "max". Only "maximum" which doesn't work.

Thanks!

 

[Red_of_Head]

Re: MATH1131 help thread

Wow I didn't know about that "~" or "max". Only "maximum" which doesn't work.

Thanks!

No worries. Should note that the "~" applies argument to each of the complex numbers. So

argument~([C1,C2,C3,C4,C5]);

is equivalent to

[argument(C1),argument(C2),argument(C3),argument(C4),argument(C5)];

 

[Flop21]

Re: MATH1131 help thread

Use quadratic formula to find all complex roots:

-2z^2+6z-3


I get the correct answer - except for the i. I don't get an i in my answer. Where does the i come in in this question??

Thanks.

 

[InteGrand]

Re: MATH1131 help thread

Use quadratic formula to find all complex roots:

-2z^2+6z-3


I get the correct answer - except for the i. I don't get an i in my answer. Where does the i come in in this question??

Thanks.

 

[Flop21]

Re: MATH1131 help thread

6^2-4(-2)*(-3) = 12 .. is not negative

hence I'm not getting the i

 

[InteGrand]

Re: MATH1131 help thread

6^2-4(-2)*(-3) = 12 .. is not negative

hence I'm not getting the i

Ah yeah, then the roots are real (no i). What do the answers say?

 

[Flop21]

Re: MATH1131 help thread

They have my same answer except with an I.

1/2*(3+-sqrt(3))*I

I'm getting 1/2*(3+-sqrt(3)) but maybe I'm making a silly mistake somewher

 

[Shadowdude]

Re: MATH1131 help thread

flop when is your maple test

 

[InteGrand]

Re: MATH1131 help thread

They have my same answer except with an I.

1/2*(3+-sqrt(3))*I

I'm getting 1/2*(3+-sqrt(3)) but maybe I'm making a silly mistake somewher

There shouldn't be an i (the roots are real). Even if there was an i, it wouldn't be something like ((non-zero) real number)*i, unless the equation was of the form where a purely imaginary solution existed, i.e. z^2 + a = 0 for some a > 0 (and the given equation isn't like this).

 

[Flop21]

Re: MATH1131 help thread

flop when is your maple test

this friday