The derivative of x squared with respect to x is 2x. The derivative of a constant with respect to x, a constant does not change with respect to x, so it's just equal to 0. You apply the derivative operator to any of these expressions, and you get 2x. Now let's go the other way around. Let's think about the antiderivative. One way to think about it is we're doing the opposite of the derivative operator. In the derivative operator, you get an expression, and you find its derivative.