Question

What is Cramer's Rule?

I have to solve the following system using Cramer's Rule.

3x + 4y = -15
2x - 7y = 19

Can anyone explain how to do this?

Answer 1

Who's anyone? :3

Answer 2

Sheesh, why are you so dead-serious? :D

Answer 3

I don't understand what you're trying to say? Lol

Answer 4

To sum it all up, what I just said plus what I think, is this:
I. AM. AWESOME.


But that aside, do you know how to calculate determinants? It's key here ^.^

Answer 5

ab - bc

Answer 6

but I thought that only applied to matrices

Answer 7

That is true, so let's make up a matrix ^.^

In particular, let's call it the coefficient matrix.

Don't argue with me now >:)

This is the coefficient matrix... do you see how I got it?
\[\Large \left[\begin{matrix}3&4\\2&-7\end{matrix}\right]\]

Answer 8

Hey, did you fall asleep just now? o.o

Answer 9

i know how to

Answer 10

That's great :D
What about you, @MadisonAdair1030 ?

Don't die on me now :3

Answer 11

I actually did fall asleep, guys. I'm sorry. I'm pregnant so my sleep schedule is a little messed up! I see how you got the matrix. You used the x and y values. But what about the -15 and 19? And why are we turning this into a matrix in the first place?

Answer 12

Oh nevermind. I just looked up the definition of Cramer's Rule and I see why we're using a matrix. Sorry about that!

Answer 13

@MadisonAdair1030 u got the method or i do it for u?