diff --git a/src/7_tight_binding_model_sol.md b/src/7_tight_binding_model_sol.md
index e6b32bd9941f8f66aee594a2620a1c22612f2556..53f6c886e32b79ce35896e58a219339599d0cb70 100644
--- a/src/7_tight_binding_model_sol.md
+++ b/src/7_tight_binding_model_sol.md
@@ -39,7 +39,7 @@ k = np.linspace(-pi+0.01, pi-0.01, 300)
 pyplot.plot(k, np.sin(k)/(np.sqrt(1-np.cos(k))));
 pyplot.xlabel('$k$'); pyplot.ylabel('$v(k)$');
 pyplot.xticks([-pi, 0, pi], [r'$-\pi/2$', 0, r'$\pi/2$']);
-pyplot.yticks([-1, 0, 1], [-r'$2\sqrt{\frac{\kappa}{m}}$', 0, r'$2\sqrt{\frac{\kappa}{m}}$']);
+pyplot.yticks([-np.sqrt(2), 0, np.sqrt(2)], [r'$-2\sqrt{\frac{\kappa}{m}}$', 0, r'$2\sqrt{\frac{\kappa}{m}}$']);
 pyplot.tight_layout();
 
 pyplot.subplot(1,2,2)
@@ -50,6 +50,7 @@ pyplot.xlabel(r'$\omega$'); pyplot.ylabel('$g(w)$');
 pyplot.xticks([-1, 0, 1], [r'$-2\sqrt{\frac{k}{m}}$', 0, r'$2\sqrt{\frac{k}{m}}$']);
 pyplot.yticks([0.5, 1], [0, r'$\frac{L}{2\pi a}\sqrt{\frac{\kappa}{m}}$']);
 pyplot.tight_layout();
+pyplot.show()
 ```
 
 4.