Here are a couple of mathematical riddles. No knowledge beyond high school algebra and geometry is required to solve them.

1) Prove that the general solution of a quadratic equation (of form ax^2 + bx + c = 0) is x = [-b +- sqrt(b^2 - 4ac)]/2a.

2) Find the area of the shaded region:



I realize that the picture is hard to read, but the square is supposed to be 40 units in length.