a) y=ax+b- równanie prostej
-5=4a+b
3=2a+b
b=-5-4a
3=2a-5-4a
b=-5-4a
8=-2a/ : (-2)
a=-4
b=-5-4*(-2)
a=-4
b=3
y=-4x+8
b) y=ax+b
-1=-9a+b
3=3a+b
b=-1+9a
3=3a-1+9a
b=-1+9a
4=12a
a=4/3
b=-1+9*4/3=11
y=4/3a+11
d) y=ax+b
5=-a+b
1=a+b
b=5+a
1=a+a+5
b=5+a
6=2a
a=3
b=5+3=8
y=3a+8