Solution
= Solution
The error equation has right side $O(h^4)$. With $\|A_h^{-1}\|_2\le C/h^2$, it follows that $\|e\|_2=O(h^2)$.
= Solution
The error equation has right side $O(h^4)$. With $\|A_h^{-1}\|_2\le C/h^2$, it follows that $\|e\|_2=O(h^2)$.