diff --git a/zadania 12.txt b/zadania 12.txt
new file mode 100644
index 0000000..5e2e51e
--- /dev/null
+++ b/zadania 12.txt	
@@ -0,0 +1,60 @@
+mathics
+1.
+
+Solve[{2x-2y+z-w==7,-x+4y-5z+3w==1,x+y-z+w==4,-4x+2y+z-2w==6},{x,y,z,w}]
+
+2.
+
+Solve[{x^3-21*x+20==0},{x}]
+
+3.
+
+Plot[ x^2-2*x+3, {x , 0 , 15}]
+
+4.
+
+Plot[ Cos[2*x], {x,-1,1}]
+
+5.
+Plot[Sin[1/x], {x,1,3}]
+6.
+
+7.
+
+octave
+1. 
+A = [2 -2 1 -1; -1 4 -5 3;1 1 -1 1;-4 2 1 -2];
+f = [7 1 4 6];
+u = A\f'
+2.
+c = [1 0 -21 20];
+roots(c)
+
+
+3.
+x=[-3:1:10];
+y=x^2-2*x+3;
+plot(x,y,".c")
+4.
+x=[0:0.1:10]
+y=cos(2*x)
+plot(x,y,"-g")
+
+
+
+5.
+
+x=[-3:0.1:10];
+y=sin(x.^(-1));
+plot(x,y,"-y")
+6.
+x = -2.0:1:2;
+y = -2.0:1:2;
+[X,Y]=meshgrid(x,y);
+mesh(X,Y,X.^2+Y.^2)
+
+7.
+x=-2:1:2;
+octave:67> y=-2:1:2;
+octave:68> [X,Y]=meshgrid(x,y);
+octave:69> mesh(X,Y,X.^2-Y.^2+2*X*Y.^2+1)