Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Zrk2]

I'm starting this because a) I can't find the old one and b) because I need help.

Can anyone explain to me how to solve matrices? Specifically I'm referring the the Ax=B and x=A^-1B. I have tried looking over my notes but they have failed to help me at all.

For example A^-1=

Code: [Select]

[-9, 2]
[-1, -8]
And B=

Code: [Select]

[-9]
[2]
What is x₂? I'm completely lost.

[zombie urist]

You're not solving matrices you're solving matrix equations.
A matrix equation is just an easier way of writing down a linear system.
a1x1 + a2x2 = b1
a3x3 + a4x2 = b2

Can be written as

Code: [Select]

[a1 a2][x1]   [b1]
[a3 a4][x2] = [b2]

In this case, x = A^-1B =

Code: [Select]

[85]
[-7]
So x2 = -7

[Zrk2]

Okay, that makes sense now. What I was doing before was super wrong.

Thanks, that clears up a lot, I hope you're as helpful when I break out the calculus tomorrow, assuming it still makes as little sense as it made in the lecture.

[i2amroy]

Thanks, that clears up a lot, I hope you're as helpful when I break out the calculus tomorrow, assuming it still makes as little sense as it made in the lecture.

Calculus is mostly just rule memorization and then learning exactly when to apply the various rules that you memorized. It really is a very fun type of math once you learn the basics, and I can safely say that Calculus III has probably been my favorite math class of all time so far. It's really very nice to go from extremely complicated algebra problems back to something that can solve in your head without one. In fact really the only reason that a lot of people find calc so hard is that it is the first time somebody asks them "now which of these 10 rules are you going to solve this problem?" instead of saying "here's a single formula, now use it to solve these 50 problems".

And if you ever don't understand something don't be afraid to ask here, I mean I know for a fact that a large percentage of these forums is knowledgeable enough to help through most problems you might encounter.

[MonkeyHead]

PTF, incase this takes off like the old one.

[MagmaMcFry]

PTF, incase this takes off like the old one.

[MetalSlimeHunt]

I'm about to bash my skull in with my calculator at this very moment, actually. Fucking linear and exponential functions. They don't work. They just plain do not fucking work. I try to view the necessary value once the function is graphed and "INVALID".

[Karlito]

What's the model of your graphing calculator?

[Zrk2]

Is it one of those TI-83s?

And I tried my homework and it was easier than expected, the prof just uses an excessive number of Greek letters when he lectures.

[MonkeyHead]

I seriously reccomend using Wolfram Alpha for help with graphing functions and as a good starting point for evaluating them. What functions is it that happen to be causing grief? I have some experience with exponenial functons for modelling a number of physical properties...

[ed boy]

I'm about to bash my skull in with my calculator at this very moment, actually. Fucking linear and exponential functions. They don't work. They just plain do not fucking work. I try to view the necessary value once the function is graphed and "INVALID".

Care to give an example?

[MetalSlimeHunt]

I'm about to bash my skull in with my calculator at this very moment, actually. Fucking linear and exponential functions. They don't work. They just plain do not fucking work. I try to view the necessary value once the function is graphed and "INVALID".

Care to give an example?

I'm not allowed to solicit outside help, so no. Mostly just complaining because of how angry it made me earlier.

[Zrk2]

It sounds more like his display grid is set wrong or something.

[Another]

PTF, incase this takes off like the old one.

[Grek]

So, let's define a monster function:

Let f(x) equal the integral of csc(x) from 1 to f(x). Find f(pi).