Răspunsuri

2014-04-27T15:59:25+03:00
A²-b²=24
3a+3b=6|:3 <=>a+b=2=>a=2-b
inlocuim a cu 2-b in prima ecuatie
(2-b)²-b²=24
folosim formula (a-b)²=a²-2ab+b²
4-4b+b²-b²=24
(+b² se reduce cu -b²)
<=> 4-4b=24
-4b=20=> b= -5
a+b=2
a-5=2=>a=7
a-b=7-(-5)= 7 + 5=12 
2 5 2