from pylab import *

def xeq1(r):
    return sqrt(r)

def xeq2(r):
    return -sqrt(r)

domain = linspace(0, 10)
plot(domain, xeq1(domain), 'b-', linewidth = 3)
plot(domain, xeq2(domain), 'r--', linewidth = 3)
plot([0], [0], 'go')
axis([-10, 10, -5, 5])
xlabel('r')
ylabel('x_eq')

show()
