Question

Ex 18 ....................​

Answer 1

x+y=4
2x-y=-1
Le aduni

3x=3
x=3/3=1

x+y=4
Y=4-x=4-1=3


Punctul b
3x+2y=14
-x+4y=14 înmulțești cu 3


3x+2y=14
-3x+12y=42

14y=56
Y=56/14=4

-x+16=14
x=2


Punctul c

5x+y=14
3x-2y=-2


10x+2y=28
3x-2y=-2


13x=26
X=26/13
X=2

5x+y=14
10+y=14
Y=14-10=4


Punctul d

-2x+y=1
X-2y=-5

-4x+2y=2
x-2y=-5

-3x=3
-x=3/3
x=-1

X-2y=-5
-1-2y=-5
-2y=4
Y=-4/2=-2