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rezolvati functia x+2y=15
2x+3y=25


Răspuns :

x + 2y = 15 (* -2) →
2x + 3y = 25

-2x - 4y = -30
2x + 3y = 25
__________ +
-2x + 2x - 4y + 3y = -30 + 25 →
- y = -5 → y = 5.

x + 2* 5 = 15 → x + 10 = 15 → x = 5

S= { (5; 5) }

x+2y=15/-3=>-3x-6y=-45
2x+3y=25/*2=>4x+6y=50
_______________________+
4x-3x-6y-6y=50-45
x=5
5+2y=15=>y=5