Given that ​f(x)=x^2-15 and ​g(x)=10−​x, find ​(f−​g)(3​), if it exists.

Answer 1

of course it exists. It's just the difference of two polynomials, so it's another polynomial.

(f-g)(3) = f(3)-g(3)

Now just plug in their values and simplify.