Question

sistem prin metoda reducerii!va rog

Answer 1

10x-12y=80
  8x+6y=20 |·2 ⇒

10x-12y=80
16x+12y=40
26x     /  =120
x=120/26
x=60/13

8x+6y=20⇒ 6y=20-8x
6y=20-8·60/13
6y=20-480/13
6y=(260-480)/13
6y=(-220)/13
y=-220/6·13
y=-110/39
x=60/13

Answer 2

Metoda reducerii (preferata mea)
Inmultim a doua ecuatie cu 2 :
10x-12y=80
16x+12y=40
_________
26x /  =120 =>x=60/13

Inmultim prima ecuatie cu 4 si a doua cu (-5) :
40x-48y=320
-40x-30y=-100
____________
/     -78y=220 =>y=-110/39