# how do you find row echelon form using TI calc?

• Jan 14th 2008, 01:12 PM
algebra2
how do you find row echelon form using TI calc?
Quote:

Originally Posted by galactus
First, write it in matrix format using the coefficients.

$\displaystyle \left[\begin{array}{ccc|c}1&5&6&10\\3&15&-2&9\\5&12&-9&5\end{array}\right]$

The idea is to use elementary row operations to hammer it into the form:

$\displaystyle \left[\begin{array}{ccc|c}1&0&0&a\\0&1&0&b\\0&0&1&c\end{ array}\right]$

Your solutions will be a,b, and c.

I feel about Gaussian eleimination the way Plato feels about partial fraction decompositions. With the technology that abounds these days, why go through the tedium of reduced row echelon?. We can spend our mathematical time more efficiently. But, you gotta do what you gotta do.

It took my TI about 2 seconds to give me:

$\displaystyle \left[\begin{array}{ccc|c}1&0&0&\frac{557}{260}\\0&1&0&\ frac{81}{260}\\0&0&1&\frac{21}{20}\end{array}\righ t]$

can you please tell me how to find the reduced row echelon form of this:

1 2 -1 | 3
7 -1 1 | 2
3 2 1 | -1

using a my TI calculator
• Jan 14th 2008, 01:33 PM
galactus
Here's the screen capture. That should help you see how to do it.

What kind of TI do you have?. This is from a TI-92. Some may work differently.
• Jan 14th 2008, 01:49 PM
algebra2
i have a TI-84 and yeah it works very differently, but i got the same answers as you except that the solutions appeared in decimals and not in fractions.

is there a way to turn them into fractions?
• Jan 14th 2008, 01:52 PM
galactus
That I can't tell you. Try googling something. The TI site has the manuals.

I think you use 'frac'. It may be under MATH

On the 92, EXACT is use.

For instance, exact(.2598) gives 1299/5000
• Jan 14th 2008, 02:06 PM
algebra2
it worked with Frac under math.

thanks.