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

2. Relevant equations

A=LU, U^-1 * L^-1= A^-1 , U^-1 * L^-1 * U^-1 * L^-1 = A^-2,

3. The attempt at a solution

I used MATLAB and the relations:

U^-1 * L^-1= A^-1 , U^-1 * L^-1 * U^-1 * L^-1 = A^-2,

to find a solution

I found U^-1*L^-1 , let =B

Then, found B^2 and took the inverse of B to get A^-2.

B=A^-1

C=inv(B^2)

so we have B*x+C*y= [2;5;10]

My question is: is there an easier way to do this? We are supposed to do this problem by hand. This would have taken a good amount fo effort to find so many inverse matrices.

Any input is appreciated!

Thank you!

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Linear algebra -- compute the following without finding invA

Have something to add?

**Physics Forums | Science Articles, Homework Help, Discussion**