And so now we can write our f of x as we get f of x is equal to negative 12, and I could even write that as negative 12 over x squared if we like. Negative 12 over x squared plus 15. And now using that, we can evaluate f of negative one. f of negative one. Wherever we see an x, we put a negative one there. So this is going to be negative one squared. So f of negative one is equal to 12 divided by, or negative 12 divided by negative one squared.