diff --git a/zajęcia 12/mathematics.txt b/zajęcia 12/mathematics.txt
new file mode 100644
index 0000000..187e8be
--- /dev/null
+++ b/zajęcia 12/mathematics.txt	
@@ -0,0 +1,19 @@
+zad.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}]
+
+zad.2
+
+Solve[x^3-21x+20==0,x]
+
+zad.3
+Clear(x) #czyszczenie zmiennej
+Plot[x^2+2x+3,{x,-4,4}]
+
+Plot[cos(2*x),{x,-4,4}]
+
+Plot[sin(1/x),{x,1,4}]
+
+Plot3D[x^2+y^2,{x,-2,2},{y,-2,2}]
+
+Plot3D[x^2-y^2+2*x*y^2+1,{x,-2,2},{y,-2,2}]
\ No newline at end of file