f1(x) = 1-x
g1(x)=-x
p1=plot(f1(x), (x,-10,10), ymin = -5, ymax = 5)
p2=plot(g1(x), (x,-10,10), ymin = -5, ymax = 5)
p1+p2

f2(x) = 1-x
g2(x)=x
p3=plot(f2(x), (x,-10,10), ymin = -5, ymax = 5)
p4=plot(g2(x), (x,-10,10), ymin = -5, ymax = 5)
p3+p4

f3(x) = 1-x
g3(x)= (2-2*x)/2
p5=plot(f3(x), (x,-10,10), ymin = -5, ymax = 5)
p6=plot(g3(x), (x,-10,10), ymin = -5, ymax = 5)
p5+p6

A = matrix([[2, 5], [4, 3]])
b = vector([2, 18])
x1 = A.solve_right(b)
print x1