The remainder theorem tells us the value of a polynomial when `x = a` is the remainder when the polynomial is divided by `x - a`.

We'll use synthetic division to divide by `x +5 = (x - (-5))`:

`-5`	`1`	`4`	`-19`	`-65`
		`-5`	`5`	`70`
	`1`	`-1`	`-14`	`5`

The last entry of the row is the remainder, `5`.

So the value of `x^3+4 x^2-19 x-65` when `x = -5` is `5`.