Răspunsuri

2014-05-21T23:23:31+03:00
2a+b-3c=15 
a-4b+8c=25 \·3 inmultim relatia cu 3

2a+b-3c=15
3a-12b+24c=75\+ adunam cele doua relatii
 
5a-11b+21c=15+75
5a-11b+21c=90