eq1: 2*x - 2*y + z - w = 7$
eq2: -1*x + 4*y - 5*z + 3*w = 1$
eq3:  x +  y -  z +  w = 4$
eq4: -4*x + 2*y +  z - 2*w = 6$
rown:[eq1,eq2,eq3,eq4]$
rozw:linsolve(rown, [x,y,z,w]);

solve(x^3-21*x+20=0);

wxplot2d([x^2-2*x+3],[x,-5,5],[y,0,20])$
wxplot2d(cos(2*x),[x,-4,4],[y,-4,4])$
wxplot2d(sin(1/x),[x,-0.1,0.1],[y,-1,1])$
wxplot3d(x^2+y^2,[x,-1,1],[y,-1,1])$
wxplot3d(x^2−y^2 + 2*x*y^2+1,[x,-3,3],[y,-3,3])$