1. ## Elementary Row Operations

I'm doing homework and checking my answers with the appendices in the back of our textbook. I have this matrix that I'm supposed to turn into an elementary matrix:

$\displaystyle \begin{bmatrix}1 & 0 & 4 \\0 & 1 & 0 \\ 0 & 0 & 1 \end{bmatrix}$

The book says 4R3 + R1 -> R1, but doesn't make into a elementary matrix. Shouldn't it be -4R3 + R1 -> R1?

2. ## Re: Elementary Row Operations

I'll just follow my gut. Maybe it's a mistake in the textbook

3. ## Re: Elementary Row Operations

Originally Posted by amthomasjr
I'm doing homework and checking my answers with the appendices in the back of our textbook. I have this matrix that I'm supposed to turn into an elementary matrix:

$\displaystyle \begin{bmatrix}1 & 0 & 4 \\0 & 1 & 0 \\ 0 & 0 & 1 \end{bmatrix}$

The book says 4R3 + R1 -> R1, but doesn't make into a elementary matrix. Shouldn't it be -4R3 + R1 -> R1?
Yes, you're correct, it should be:

$\displaystyle R_1 \to R_1 - 4R_3$