How do you find the domain of #f(x) =sqrt(9 - x)#?
To find the (real) domain, we need to make sure we
(1) don't try to take even roots of negative numbers (square roots, 4th, 6th, 8th and so on)
(2) don't try to divide by zero
(and more rarely avoid other undefined expressions like
We need to make sure that
So we need to make sure that
(I prefer to avoid negatives in front of the
Let's make it look like what it ays, by writing it this way:
all (real) numbers,
There are other ways of expressing the answer, but they all refer to the same set of numbers"
It may seem or 'feel' a little odd that we could use, for example,
Before we take the square root, we're going to find
We could not use