Binomial Theorem

	$\displaystyle (x+y)^2=x^2+2x+y^2$		$\displaystyle (x-y)^2=x^2-2xy+y^2$
	$\displaystyle (x+y)^3=x^3+3x^2y+3xy^2+y^3$		$\displaystyle (x-y)^3=x^3-3x^2y+3xy^2-y^3$
	$\displaystyle (x+y)^4=x^4+4x^3y+6x^2y^2+4xy^3+y^4$		$\displaystyle (x-y)^4=x^4-4x^3y+6x^2y^2-4xy^3+y^4$
	$\displaystyle (x+y)^n=x^n+nx^{n-1}y+\frac{n(n-1)}{2!}x^{n-2}y^2+\cdots +nxy^{n-1}+y^n$
	$\displaystyle (x-y)^n=x^n-nx^{n-1}y+\frac{n(n-1)}{2!}x^{n-2}y^2-\cdots \pm nxy^{n-1}\mp y^n$