Thread: Elimination method with 3 equations

http://i1209.photobucket.com/albums/...g?t=1333868898

I've tried this problem about 6 times and can't get the right answer in the book, can someone please show me how to do this...

Originally Posted by batosaims

http://i1209.photobucket.com/albums/...g?t=1333868898

I've tried this problem about 6 times and can't get the right answer in the book, can someone please show me how to do this...

Multiply 2nd. by -3 and add to the 1st. ,also..multiply 2nd. by 4 and add to the 3rd. :



Add 2nd to the 3rd. :



So , solution of the system is :

Originally Posted by princeps

Short cut; add 1st 2 equations to get:
4a + 2b - 2c = 2 ;add to 3rd equation:
-4a+ 6b +2c = -6
=============
8b = -4
b = -1/2 (as per Princeps)