In[]:=
Show[{​​ContourPlot[
2
x
+
2
y
1,{x,-2,2},{y,-2,2}],​​ContourPlot[
2
x
-
2
y
1,{x,-2,2},{y,-2,2}]​​}​​]
Out[]=
In[]:=
Show@ContourPlot[
2
x
+
2
y
1,{x,-2,2},{y,-2,2}]
Out[]=
In[]:=
Table
2
x
+
2
y

2
k
,k,0,2,
1
4

Out[]=

2
x
+
2
y
0,
2
x
+
2
y

1
16
,
2
x
+
2
y

1
4
,
2
x
+
2
y

9
16
,
2
x
+
2
y
1,
2
x
+
2
y

25
16
,
2
x
+
2
y

9
4
,
2
x
+
2
y

49
16
,
2
x
+
2
y
4
Show@ContourPlot
2
x
+
2
y
0,
2
x
+
2
y

1
16
,
2
x
+
2
y

1
4
,
2
x
+
2
y

9
16
,
2
x
+
2
y
1,
2
x
+
2
y

25
16
,
2
x
+
2
y

9
4
,
2
x
+
2
y

49
16
,
2
x
+
2
y
4,​​{x,-4,4},{y,-4,4}
Out[]=
In[]:=
Show​​ContourPlot​​Evaluate@Table
2
x
+
2
y

2
k
,k,0,2,
1
4
,​​{x,-2,2},{y,-2,2},​​ContourPlot​​Evaluate@Table
2
x
-
2
y

2
k
,k,0,2,
1
4
,​​{x,-2,2},{y,-2,2}​​
Out[]=
In[]:=
Show[{​​ContourPlot[
2
x
+
2
y
2,{x,-2,2},{y,-2,2}],​​ContourPlot[
2
x
-
2
y
1,{x,-2,2},{y,-2,2}]​​}​​]
Out[]=
In[]:=
Solve[{
2
x
+
2
y
2,
2
x
-
2
y
1},{x,y}]
Out[]=
x-
3
2
,y-
1
2
,x-
3
2
,y
1
2
,x
3
2
,y-
1
2
,x
3
2
,y
1
2

In[]:=
solns:=Solve[{
2
x
+
2
y
2,
2
x
-
2
y
1},{x,y}]
Graphics[Point[{x,y}]/.solns]
Trying to do (the more normal) matrix multiplication on the left:
This definition of a rotation-matrix function using lists works.