Homework Help

[Mlp_fan101 55]

7 hours ago, mini said:

Introduction and setting are portrayed much better. I feel like I understand the character's world more. I like how the character's thoughts are spontaneously disrupted by "Stop," followed by a return to business as usual. This sense of duty foreshadows the conclusion. However, I'd like to change some parts if you don't mind.

 

This version is markedly better. I'm not sure why your teacher is refusing to give you proper feedback. sounds like a shit teacher tbh

Wow I actually can’t thank you enough for your help!  you have a real literary talent and I’m so grateful you’ve shared it with me

[Lucky Bolt 34,914]

Okay, this is probably a long shot but I'm desperate for any help.

So does anyone here use LibreOffice Calc for spreadsheets? I have a spreadsheet project due on Monday and I can't figure out how to resize the spreadsheet cells and columns properly. I tried googling how to but nothing I read was much of a help.  Either that or I'm just too dumb lol

[Misty Gust 708]

2 minutes ago, Lucky Bat said:

Okay, this is probably a long shot but I'm desperate for any help.

So does anyone here use LibreOffice Calc for spreadsheets? I have a spreadsheet project due on Monday and I can't figure out how to resize the spreadsheet cells and columns properly. I tried googling how to but nothing I read was much of a help.  Either that or I'm just too dumb lol

Can you just click and drag the lines like in Excel?

[Lucky Bolt 34,914]

Just now, Misty Breeze said:

Can you just click and drag the lines like in Excel?

What lines though? Cause I kept reading something about click and drag the borders and I'm like WHAT BORDERS 

[Misty Gust 708]

Just now, Lucky Bat said:

What lines though? Cause I kept reading something about click and drag the borders and I'm like WHAT BORDERS 

Like the line around each cell. 

Or try at the top and on the side where the row an column labels are like A, B, C, etc and 1, 2, 3, etc click and drag the line between those.

At least that's how Excel works.

[Lucky Bolt 34,914]

5 minutes ago, Misty Breeze said:

Like the line around each cell. 

Or try at the top and on the side where the row an column labels are like A, B, C, etc and 1, 2, 3, etc click and drag the line between those.

At least that's how Excel works.

I don't think that's how Libreoffice works. Either I'm just not seeing it or....it's an Excel thing 

[CypherHoof 26,479]

2 minutes ago, Lucky Bat said:

I don't think that's how Libreoffice works. Either I'm just not seeing it or....it's an Excel thing 

Just checked on a copy of libreoffice - if you move the cursor to the line between (say) A and B on the top bar, it turns into a double headed arrow like <--> ... if at that point you click and drag, it resizes the column to the left (A). same thing between the numbers

 

                  

[Lucky Bolt 34,914]

11 minutes ago, CypherHoof said:

Just checked on a copy of libreoffice - if you move the cursor to the line between (say) A and B on the top bar, it turns into a double headed arrow like <--> ... if at that point you click and drag, it resizes the column to the left (A). same thing between the numbers

 

                  

Oh my gosh thank you! That’s exactly what I was looking for! You’re a lifesaver 

[CypherHoof 26,479]

5 minutes ago, Lucky Bat said:

Oh my gosh thank you! That’s exactly what I was looking for! You’re a lifesaver 

NP, happy I could help

[Lucky Bolt 34,914]

Oh look who's back in here again.  

I have a research paper due in a couple days. It's on potential planets (other than Earth of course ) that could support life. Does anyone know of any good online sources where I could get some legitimate research info on this topic? I did find a couple things on the National Geographic website but I need more sources. I'm just curious if any of you know of any. Thanks! 

[Jesse Terrence 2,963]

12 minutes ago, Lucky Bells said:

Oh look who's back in here again.  

I have a research paper due in a couple days. It's on potential planets (other than Earth of course ) that could support life. Does anyone know of any good online sources where I could get some legitimate research info on this topic? I did find a couple things on the National Geographic website but I need more sources. I'm just curious if any of you know of any. Thanks! 

Have you tried the NASA official website? Sometimes they post articles for the general public regarding that kind of stuff.

[Lucky Bolt 34,914]

59 minutes ago, Jesse Terrence said:

Have you tried the NASA official website? Sometimes they post articles for the general public regarding that kind of stuff.

Ooh, Didn’t think of that. I’ll check it out, thanks! 

[MynnieMonster 15]

I'm pretty good in biology, zoology, and environmental science. I could help tutor if needed! Though the latter two are rather unconventional and I know not every school teaches those subjects I figured I could offer anyways. I'm currently at a senior level of high school so all the science I know doesn't reach into college level yet.

[Mirage 24,137]

I could use a hand with my Engineering homework:

5. Compute the magnitude of the following complex numbers:

a. 2 + j5

b. e jπ

c. 3ejπ/2

d. j 5/8

6. Simplify to a + jb form:

a. (2+j)/(1+j2) + (1+j)

b. e jπ/2 + j

c. (4+j3)/(1-j)

d. e jπ + (1+j)/(1-j)

While I understand all this in concept, my stumbling block is simplifying to fractional form in Radians. Need some pointers/cheat sheets about that.

[Pentium100 2,057]

It's been a while since I needed this, but let's try.

Disclaimer: I may have made some mistakes, missed a sign or something. If you give my answer to your teacher without verifying I am not responsible for a bad grade.

The magnitude of a complex number of the form (a+bj) can be calculated with Sqrt(a^2+b^2).

4 hours ago, Mirage said:

a. 2 + j5

b. e jπ

c. 3ejπ/2

d. j 5/8

a. Sqrt(2^2 + 5^2) = Sqrt(29)
b. Now this I can interpret two ways, either it is e*j*pi, in which case the magnitude is e*pi or, e^(j*pi), in which case the magnitude is 1. But I'm guessing that this and the other numbers with e in them are polar notation, just that the superscript formatting is lost here.
c. 3e^(j*pi/2) , the magnitude of this is 3. In polar notation, the magnitude is the number that e is multiplied by (in b it was 1) and the angle is what j is multiplied by.
d. OK, I have two ways to read this one as well, it's either j*5/8, in which case the magnitude is 5/8 or j^(5/8). This you can calculate like this: 
, in which case the magnitude is 1.

4 hours ago, Mirage said:

While I understand all this in concept, my stumbling block is simplifying to fractional form in Radians. Need some pointers/cheat sheets about that

The idea is this: You need to find the magnitude and the angle. You can find the magnitude by Sqrt(a^2+b^2) and the angle usually by arctan(b/a). However, this fails is a is zero. This is where you have to know three special cases:
0 + x*j, the angle is pi/2
0 - x^j, the angle is -pi/2 or 3pi/4 (they are equivalent)
0 + 0*j, the angle is undefined
all the other cases should work with arctan(b/a).

4 hours ago, Mirage said:

6. Simplify to a + jb form:

a. (2+j)/(1+j2) + (1+j)

1+j2 is either 1+j^2 or 1+j*2. If it's the first one, then 1+j^2 = 1-1 = 0 and you get division by zero, so let's assume it's the second one.
Let's convert 2+j and 1+j*2 to polar notation:
2+j. Magnitude = Sqrt(2^2+1^2)=Sqrt(5). Angle = arctan(1/2) (it does not evaluate to something pretty)
1+j2. Magnitude = Sqert(1^2 + 2^2)=Sqrt(5). Angle = arctan(2)

Now, there is a formula with arctan difference. It is: arctan α - arctan β = arctan [(α-β) / (1+αβ)], let's apply it here.

Still does not evaluate into something nice. Oh well. The number is    

Now we need to convert it to a+bi form.

Polar notation m*e^(j*phi) converts into Cartesian notation (?) like this:
a=m*cos(phi)
b=m*sin(phi)
And we get to use a couple of formulas here:

Let's go:

So, 

Now we just need to add the remaining part:

0.8 - 0.6j +  (1+j) = 1.8 + 0.4j

4 hours ago, Mirage said:

b. e jπ/2 + j

This one's easier:

a=cos(pi/2)=0
b=sin(pi/2)=1
e^(j*pi/2)=j
j+j=2j
e jπ/2 + j = 2j

4 hours ago, Mirage said:

(4+j3)/(1-j)

Again, this can be j*3 or j^3. Let's say it's j^3 this time:

Let's try to solve this a bit different, like a normal fraction. Multiply both parts by (1-j). We'll take advantage of the fact that j^2 = -1 and the fact that 1/j = -j.

4 hours ago, Mirage said:

e jπ + (1+j)/(1-j)

This seems easy, let's try:

 (this is known as Euler's identity)

 

I think I got all of them correctly, but I may have made a mistake with signs or something, You should verify this.

Disregard everything after this line - I made some mistakes and pasted the fixed equations, but I cannot find them among the attachments (because the thumbnails show only a tiny portion) to delete them.

Edited February 15, 2020 by Pentium100
Hid the wrong equations

[Mirage 24,137]

@Pentium100 Thank you so much! That was much more help than I expected. I shall review and check my work against yours. I'm truly very grateful of your instruction. A true Twilight in our midst!

[Wayzer 1,418]

I’d totally help out with homework too if I wasn’t so bad with math >~> I study medicine though so it anybody needs help with subjects going in that direction I’d gladly provide it!

[Splashee 28,537]

On 2/16/2020 at 12:12 AM, Pentium100 said:

Disclaimer: I may have made some mistakes, missed a sign or something. If you give my answer to your teacher without verifying I am not responsible for a bad grade.

@Pentium100, you are the best!
I keep learning from your math examples. You know that, right? Just want to make sure, your post there never goes to waste!

[Pentium100 2,057]

9 hours ago, Super Splashee said:

I keep learning from your math examples. You know that, right? Just want to make sure, your post there never goes to waste!

Well, as long as the post was useful at least once, it's good.

[Venomous 18,813]

This isn’t necessarily about homework but I am taking an exam tomorrow (boards). It’s a 150 question exam and I have 3 hours to take it at a testing location. I have done my own studying but I am looking for resources that can give tips & tricks on how to pass/get through a multiple choice test. If anyone can give me something, I’d really appreciate it. 

Here is an example of what I am looking for: https://www.businessinsider.com/4-ways-to-outsmart-any-multiple-choice-test-2015-6

[Emerald Heart 24,588]

How am I just discovering this thread?

I'll prolly be using it soon for Maths

[Feather Spiral 1,892]

16 hours ago, Bakugou Is My Man ❤ said:

This isn’t necessarily about homework but I am taking an exam tomorrow (boards). It’s a 150 question exam and I have 3 hours to take it at a testing location. I have done my own studying but I am looking for resources that can give tips & tricks on how to pass/get through a multiple choice test. If anyone can give me something, I’d really appreciate it. 

Here is an example of what I am looking for: https://www.businessinsider.com/4-ways-to-outsmart-any-multiple-choice-test-2015-6

I found this: https://intranet.birmingham.ac.uk/as/libraryservices/library/asc/documents/public/Short-Guide-Multiple-Choice.pdf

TBH it... doesn't seem all that much different from a guide for preparing any old exam? Particularly highlighting key vocabulary and concepts, trying to find or make up questions to practice...

It's also crucial to read the questions and understand them - I saw much of that was lacking during my limited time as a replacement teacher. The only significant difference to me, is the ability to proceed by elimination during the test. (I find MCQ to be the easiest kind for that reason, they accommodate my terrible memory.)

The article says to cover up the answers while you read the question, and try guessing before you see the "spoilers" below. But that might not work out for you, if you're like me...

The best piece of advice though, find out whether negative marking will be used. "If your exam penalises wrong answers, only answer questions if you are reasonably confident that you have figured out the correct answer. If negative marking is not used in your exams, answer all questions, even if you have to guess" (it gives you a chance to get the points).

[Emerald Heart 24,588]

Does anyone understand how they got to this answer? I'm still confused on how this works.

Like, how did they eliminate those numbers? 

 

[Pentium100 2,057]

19 minutes ago, Emerald Heart said:

Like, how did they eliminate those numbers? 

I'll try to explain.

Lets say I want to multiply 5/2 by 4/7. What I could do normally is (5*4)/(2*7) = 20/14, but I then should simplify the fraction - Find the greatest common divisor or 20 and 14 adn divide both of them by it. In this case GCD is 2, so I can divide both numbers by it and get the final result 10/7.

In your example this was done during the calculation, not after.

Let's repeat (5/2)*(4/7) doing that. (5*4)/(2*7), now, what I could do is divide 4 and 2 by 2, getting 2 and 1 so (5*2)/(1*7) = 10/7

This is what they did:

5/12 * 8/7 = (5*8)/(12*7). Since 5 and 7 are prime and 8 and 12 are not (and not co-prime either since they both can clearly be divided by 2), I can simplify the fraction now instead of multiplying and then simplifying, because simplifying 8/12 is easier than 40/84. So GCD(8,12) is 4, 8/12 = 2/3. 

(5*2)/(3*7) = 10/21

If it helps you, you can thing that by multiplying two fractions, you can interchange their numerators and denominators, for example:

5/12 * 8/7 = 5/7 * 8/12. Since 5/7 cannot be simplified, but 8/12 can, then simplify that and get the result.

Or, it is perfectly fine to first calculate 40/84 and then simplify that, but it usually is more difficult to find the GCD of larger numbers.

I hope I answered the right question.

Edited April 26, 2020 by Pentium100

[Emerald Heart 24,588]

Does anyone understand any of this?

I've tried and tried but I can't get it right.