(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

solve the det

3 1 1 0

-4 5 0 -1

0 7 2 8

2 -1 0 3

2. Relevant equations

3. The attempt at a solution

I am trying to solve it and get a different answer each time so I am doing something I shouldn't obviously.

Ok I am adding rows to other rows

(ex 2*row1 +row2)

Same I do for columns.

When I expend the matrix I pay attention to the + and -

So what is wrong :S

This is what I did (I didn't choose the shortest way because I wanted to make sure I am solving it right but hence something is off :S)

I did 2*R_{4}+r_{2},R_{3}-2*R_{1}

I opened the det by a_{3,1}

And got to this by this point:

1*-4 5 -1-6 5 80 3 5 then I did

R_{1}-R_{2},3*R_{1}+R_{2}

then opened it by a_{2,1}

I got the det:

6*5 -193 5Which is 492 (should b 82)

Now in all the cases I tried I reached 82 before multiplying the number outside the 2x2 det (6 in this case)

Well it is kinda hard showing the steps of the det though it is a simple one but mainly is there something wrong with the steps I take?

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# Homework Help: How do I simplify 4x4 det before solving? I am doing somethingwrong

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