And so let's do that, just to see what his answer should have been. So what he should have done here, I'll get my correcting red pen out here, say no, that's not what he should have done. He says let's take the derivative of this first thing. So actually let me do it, color code it. So the derivative of this is two x plus five. So it should have been two x plus five, times the second thing, so times sine of x, times, let me do it in another color, times sine of x. And then to that, he would add the first thing, which is x squared plus five x, times the derivative of the second thing.