Question

rezolvati prin 2 metode sistemul de ecuatie 

$\left \{ {{x+y=5} \atop {3x-2y=-1}} \right.$

Answer 1

x=5-y si inlocuim in ec doi
3(5-y)-2y=-1
15-3y-2y=-1
15-5y=-1
-5y=-1-15
-5y=-16
y=16/5

x=5-16/5=25-16/5=9/5
x=9/5



metoda 2

$\left \{ {{x+y=5} \atop {3x-2y=-1}} \right.$
inmultim  prima ec cu 2
$\left \{ {2x+2y=10} \atop {3x-2y=-1}} \right.$
adunam ecutiile
---------------------
5x=9
x=9/5

in prima ec inlocuim x si avem
y=5-9/5
y=16/5

Answer 2

x + y  = 5   | *2
3x - 2y = - 1

2x + 2y = 10
3x - 2y = - 1
_______________
5x   /   = 9
x = 9/5
9/5 + y = 5
y = 5 - 9/5
v = 25/5 - 9/5
y = 16/5