And what's the antiderivative of sine of x? Well we know from our derivatives that the derivative with respect to x of cosine of x is equal to negative sine of x. Negative sine of x. So can we construct this in some way so this is a negative sine of x? Well what if I multiplied on the inside, what if I multiplied it by negative one? Well I can't just multiply it only one place by negative one I need to multiply by negative one twice so I'm not changing its value. So what if I said negative nine times negative sine of x?