Linear algebra-2x2 RREF matrices

In summary: That would cover all possible cases. In summary, the 2x2 reduced row echelon matrices can be described by listing the following forms: 1 00 10 10 01 a0 0where a is any nonzero number.
  • #1
pyroknife
613
3

Homework Statement


Give examples to describe all 2 × 2 reduced row
echelon matrices


The Attempt at a Solution



Not sure how to type matrices on here.
I came up with 5 different ones:

0 0
0 0

1 0
0 1

0 1
0 0

1 0
0 0

1 1
0 0
Are there any I'm missing? i can't think of any more than these 5 matrices. Also the problem asks me to give examples to describe all 2x2 RREF matrices. How do I "describe" it or is providing all 5 matrices sufficient>?
 
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  • #2
I would consider "describing" all 2x2 RREF matrices as simply listing them, so I would think that you are done.

Could you quote the problem exactly?
 
  • #3
What about:

1 a
0 0

where a is nonzero and not 1?
 
  • #4
Truth [itex]\downarrow[/itex]

Dick said:
What about:

1 a
0 0

where a is nonzero?
 
  • #5
christoff said:
I would consider "describing" all 2x2 RREF matrices as simply listing them, so I would think that you are done.

Could you quote the problem exactly?
I copy and pasted the instructions. I think all I need to do is list them, but I'll check with my prof tomorrow.
Dick said:
What about:

1 a
0 0

where a is nonzero and not 1?

! DAng it. Would've never thought of that one. Using that matrix means there are infinite matrices of that form. Or I can classify it as one form with a variable.
 
  • #6
pyroknife said:
Hey, I copy and pasted the instructions. I think all I need to do is list them, but I'll check with my prof tomorrow. ! DAng it. Would've never thought of that one. Using that matrix means there are infinite matrices of that form. Or I can classify it as one form with a variable.

Sure, list it like that. Then you can drop:

1 1
0 0

It's a special case.
 
  • #7
Dick said:
Sure, list it like that. Then you can drop:

1 1
0 0

It's a special case.
Thanks a bunch for the help guys.

What do you mean by special case?

Or could I also drop
1 0
0 0
and define a is any number?
 
  • #8
pyroknife said:
Thanks a bunch for the help guys.

What do you mean by special case?

Or could I also drop
1 0
0 0
and define a is any number?

Good idea!
 

1. What is a 2x2 matrix?

A 2x2 matrix is a rectangular array of numbers or variables arranged in two rows and two columns. It is commonly used in linear algebra to represent systems of linear equations.

2. What does RREF stand for?

RREF stands for Reduced Row Echelon Form. It is one of the standard forms for representing a matrix and it has several useful properties for solving systems of linear equations.

3. How do you find the RREF of a 2x2 matrix?

To find the RREF of a 2x2 matrix, you can use Gaussian elimination, which involves performing elementary row operations on the matrix until it is in its reduced form. This includes operations such as swapping rows, multiplying a row by a constant, and adding one row to another.

4. What are the properties of a 2x2 RREF matrix?

A 2x2 RREF matrix has several properties that make it useful for solving systems of linear equations. These include having a leading 1 in each row, having zeros below each leading 1, and having the leading 1s occur in columns to the right of previous leading 1s. Additionally, the last row of the matrix will contain either all zeros or all zeros except for the last entry, which will be a 1.

5. How can RREF matrices be used to solve systems of linear equations?

RREF matrices can be used to solve systems of linear equations by representing the equations in matrix form and using Gaussian elimination to reduce the matrix to its RREF form. This allows for a systematic way to solve the equations and find the values of the variables in the system.

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