4x - y = 1
x + 2y = 7
how could i solve this using an inverse matrix?

Question

tkhunny · Answer

1) Use the coefficients to form a 2x2 matrix.
2) Augment this matric by I2
3) Perform row operations to find the inverse of the original matrix.

Are we ringing bells?

anonymous · Answer

No..

anonymous · Answer

would you write the matrix as  4  -1
                                             1    2

tkhunny · Answer

That is part #1.  Very good.  Next...

anonymous · Answer

what do you mean by augment it by I2?

tkhunny · Answer

$$\left[\begin{matrix}4 & -1 & 1 & 0\ 1 & 2 & 0 & 1\end{matrix}\right]$$

anonymous · Answer

why did you do that? sorry i'm confused

tkhunny · Answer

Well, this is one very useful way to find an Inverse Matrix.  You've never seen it, before?

anonymous · Answer

I may have but I forgot how to do it

tkhunny · Answer

How about "Elementary Row Operations"?  Any of those floating around in your bag of tricks?

anonymous · Answer

I wish I could say yes but no. I'm retaking a pre-calc course because i failed it the first time

tkhunny · Answer

Well, you're going to have to get a few things up to speed. Finding an inverse matrix is an important skill. You'll have to start somewhere. Try this: http://www.youtube.com/watch?v=RsTdy2r9DHk

anonymous · Answer

ok thanks!!