Cześć!
a)
4x+y=5
2x-y=-2
+-------
4x+2x+y-y=5-2
6x=3
x=3/6 po skróceniu: x=1/2
2*1/2-y=-2
1-y=-2
-y=-2-1
-y=-3
y=3
b)
2x+3y=5
-2x+y=-1
+-------
2x-2x+3y+y=5-1
4y=4
y=1
-2x+1=-1
-2x=-1-1
-2x=-2
x=1
c)
x-2y=3 /*(-3)
3x+5y=-2
-3x+6y=-9
3x+5y=-2
+---------
-3x+3x+6y+5y=-9-2
11y=-11
y=-1
X-2*(-1)=3
x+2=3
x=3-2
x=1
d)
3x+y=-13 /*(-3)
2x+3y=-4
-9x-3y=39
2x+3y=-4
+------
-9x+2x-3y+3y=39-4
-7x=35
x=-5
3*(-5)+y=-13
-15+y=-13
y=-13+15
y=2
Pozdrawiam!