I love the fact that the binomial expansion formula here is totally incorrect. Graduating do be like that, because you've already forgotten things you "learned" and "know".
For the unknowing, the actual formula is a^2 + b^2 = c^2. The one presented here doesn't work because if, say, a and b are both 2 (aka 2^, which is 4), then 4^2 would be 8, which it isn't. It's 16. So the formula here would basically mean that if a and b were both 2, 4+4=16. Which, you know, is incorrect. But that's the point of the joke.
Assuming that the left side of the equation is correct, the right side should read a² + 2ab + b². a² + b² = c² is most famously the Pythagorean theorem, which you use to figure out the sides of a right triangle.