diff --git a/ex8/cofiCostFunc.m b/ex8/cofiCostFunc.m
index 02d14a6..0f171af 100644
--- a/ex8/cofiCostFunc.m
+++ b/ex8/cofiCostFunc.m
@@ -40,7 +40,9 @@ Theta_grad = zeros(size(Theta));
 %                     partial derivatives w.r.t. to each element of Theta
 %
 
-J = 0.5 * sum(sum(R.*(X*Theta'-Y).^2));
+J = 0.5 * sum(sum(R.*(X*Theta'-Y).^2)) ...
+    + 0.5 * lambda * sum(sum(Theta.^2)) ...
+    + 0.5 * lambda * sum(sum(X.^2));
 
 X_grad = (R.*(X*Theta'-Y))*Theta;  % mov X user * uxer X feat = mov X feat
 Theta_grad = (R.*(X*Theta'-Y))'*X;  % user X mov * mov X feat = user X feat