MORE (Optional):
A). This is an L-Tromino; assume each square in the L-Tromino has side length 1:
Start with a square board with dimensions $2^n \times 2^n$, where n is a positive integer.
Remove one $1 \times 1$ square from any part of the board. Prove by mathematical induction
that the board can be tiled with L-trominoes.
