What did you learn today??....add yours to the list!

[Depleted]

Its that little number in the upper corner that means "to the power of". For example, an exponent of 2 means "squared".. 2x2. I'm sure u already knew this.

Yeah, but they weren't numbers. They were letters. Thus my confusion.

(I vaguely remember A, B, C, X, Y, Z, but I've never gone as far as to see M or N.)

I'd rather go back to relearn (because I can never remember the rules) gerunds and participle phrases.

 

[zeroturbulence]

Yeah, but they weren't numbers. They were letters. Thus my confusion.

(I vaguely remember A, B, C, X, Y, Z, but I've never gone as far as to see M or N.)

I'd rather go back to relearn (because I can never remember the rules) gerunds and participle phrases.

The letters just represent numbers in a formula/equation. It's algebra.

Like if I say A+B=C, and A is 1, and B is 2, what is C? The answer is C=3.... 1+2=3.

Then I could say what if A is 4? Then 4+2=6, so in that case C=6..

 

[EmilyNats]

Here is the problem... I will forever be indebted to anyone who can help me, since nobody else seems to be able to. I'm sure it's probably fairly simple and I am going to kick myself later for not being able to figure it out on my own.

Find the cubic equation that has -1 and 2i as roots.

A. y = X^3 - X^2 + 4x - 4
B. y = X^3 + X^2 - 4x - 4
C. y = X^3 + X^2 + 4x + 1
D. y = X^3 + X^2 + 4x + 4
E. y = X^3 - X^2 + 4x - 1

 

[Yahweh_is_gracious]

Here is the problem... I will forever be indebted to anyone who can help me, since nobody else seems to be able to. I'm sure it's probably fairly simple and I am going to kick myself later for not being able to figure it out on my own.

Find the cubic equation that has -1 and 2i as roots.

A. y = X^3 - X^2 + 4x - 4
B. y = X^3 + X^2 - 4x - 4
C. y = X^3 + X^2 + 4x + 1
D. y = X^3 + X^2 + 4x + 4
E. y = X^3 - X^2 + 4x - 1

I get the answer of "A" and "D". Here's how I worked through it, and I hope it is right (and that someone with more math-fu can correct me if I am in error):

If 2i is a root, then so is -2i. Similarly, if -1 is a root, then 1 is too. So I take those two roots of 2i and multiply the binomials:

(x+2i)*(x-2i) -> x^2-2ix+2ix-4i (FOIL method) -> x^2+4 (because i=sqrt(-1) and a sqrt*sqrt undoes the root)

Now take that polynomial (x^2+4) and multiply it by a binomial containing your other root (-1):

(x^2+4)*(x-1) -> x^3+4x-x^2-4 (FOIL method) -> x^3-x^2+4x-4 -> choice "A"

(x^2+4)*(x+1) ->x^3+4x+x^2+4 (FOIL method) -> x^3+x^2+4x+4 -> choice "D"

 

[Lynx]

When a bug is reported in a program and you can't make it happen for you so you can fix it, you say "cannot reproduce" or "cannot replicate." Mom was certain it was something else, some synonym of replicate, but we never found out what she was trying to think of.

But in my google searching I learned the term heisenbug.

https://en.wikipedia.org/wiki/Heisenbug

 

[zeroturbulence]

When a bug is reported in a program and you can't make it happen for you so you can fix it, you say "cannot reproduce" or "cannot replicate." Mom was certain it was something else, some synonym of replicate, but we never found out what she was trying to think of.

But in my google searching I learned the term heisenbug.

https://en.wikipedia.org/wiki/Heisenbug

I have a strong feeling the real reason they chose that name is because of Breaking Bad..

 

[Lynx]

I have a strong feeling the real reason they chose that name is because of Breaking Bad..

View attachment 166295

Today I also learned what Breaking Bad is, thanks to wikipedia. Wow, what a cheerful show...

 

[EmilyNats]

I get the answer of "A" and "D". Here's how I worked through it, and I hope it is right (and that someone with more math-fu can correct me if I am in error):

If 2i is a root, then so is -2i. Similarly, if -1 is a root, then 1 is too. So I take those two roots of 2i and multiply the binomials:

(x+2i)*(x-2i) -> x^2-2ix+2ix-4i (FOIL method) -> x^2+4 (because i=sqrt(-1) and a sqrt*sqrt undoes the root)

Now take that polynomial (x^2+4) and multiply it by a binomial containing your other root (-1):

(x^2+4)*(x-1) -> x^3+4x-x^2-4 (FOIL method) -> x^3-x^2+4x-4 -> choice "A"

(x^2+4)*(x+1) ->x^3+4x+x^2+4 (FOIL method) -> x^3+x^2+4x+4 -> choice "D"

I can only pick one choice, but that does open some things up for me. I knew I was supposed to be multiplying something, and have no idea why I didn't think to use conjugates. Going to have to do a little more thinking on a few "why" things,but thanks for shedding some light on this!

 

[zeroturbulence]

Wow we're actually trying to figure out that math? I like math but that's way beyond my skill level..

 

[EmilyNats]

So after several hours of googling and straining my brain to no avail, a grand revelation suddenly came to me. I was right, it was a simple solution hidden amongst a seemingly complicated problem. All I had to do was substitute -1 and 2i out for x and see which equation satisfied both roots.

 

[EmilyNats]

And the answer was D BTW.

 

[zeroturbulence]

So after several hours of googling and straining my brain to no avail, a grand revelation suddenly came to me. I was right, it was a simple solution hidden amongst a seemingly complicated problem. All I had to do was substitute -1 and 2i out for x and see which equation satisfied both roots.

And the answer was D BTW.

You are now my hero, Emily!!

 

[cinder]

Today I learned that it is way too easy to get another credit card. Well okay, I think I already knew that, but I'm not sure whether to enjoy the practical experience of it or to be a bit disconcerted by it. Now I have the ability to build up lots more debt (theoretically, though I'm sure my other CC company would have been happy to raise my limit if I'd asked or just gotten close to it).

 

[ROSSELLA]

Today I learned that, when you have a song stuck in your head, you're supposed to sing "Amazing Grace" to the tune of Gilligans Island. Now I have this stuck in my head:

[video=youtube;Qq61SPB3XDw]https://www.youtube.com/watch?v=Qq61SPB3XDw[/video]

 

[Galatea]

The Thirty-Nine Steps by John Buchan is really not very much like the Hitchcock film.

 

[Infusion]

I learned that I dont really have friends or family except 2 people. You know when the storm comes and they are tested.

 

[Infusion]

Today I learned that it is way too easy to get another credit card. Well okay, I think I already knew that, but I'm not sure whether to enjoy the practical experience of it or to be a bit disconcerted by it. Now I have the ability to build up lots more debt (theoretically, though I'm sure my other CC company would have been happy to raise my limit if I'd asked or just gotten close to it).

.
They are easy to get for a reason. I cant get approved for a carwash card but I can get a credit card in minutes.

 

[Infusion]

When a bug is reported in a program and you can't make it happen for you so you can fix it, you say "cannot reproduce" or "cannot replicate." Mom was certain it was something else, some synonym of replicate, but we never found out what she was trying to think of.

But in my google searching I learned the term heisenbug.

https://en.wikipedia.org/wiki/Heisenbug

.
I never heard that. Most people I know just say "cannot find the bug". =D
programming sucks! ( in C#)
not as much as math

 

[Galatea]

Wal-Mart sells escargot. They come in a cylindrical plastic tube. I didn't buy any, I ain't that swanky. I was buying tuna fish- but the solid white albacore, so a little swanky.

 

[Willie-T]

I learned how easy it is to repair (clean) the electrical contacts on your water pump.