Find the domain of the function.

So, you need to know where the function is defined. Where are radicals with even roots not defined? When they are less than 0. So, you need to set u > 0 and 9-u>0. So, the domain for the sqrt u would be x>0. The domain for sqrt 9-u would be to solve when 9-u>0

When u is less than 9, the radicand stays positive. So x>9. You need to follow the restrictions for both the radicals, so choose the one with more restrictions.

I really dont understand this. It is sort of confusing

The domain is the set of numbers you are allowed to input into the function, does that make sense?

For instance...1/x...what number are you NOT allowed to input?

For 1/x, you are not allowed to have x=0. So, the domain would be all number except 0.

So, for a square root, let's just say sqrt x...we know we are not allowed to take the square root of a negative number.

So, the domain would be all positive numbers.

For your problem, you are given 2 functions. You need to figure out what numbers are you allowed to plug in so that those square roots are legit.

Oh! I am going to have to try to get a better understanding of these problems.. THANKS

The answer wasnt all positive numbers....it was [0,9]

yes, sweetie, scroll up..was giving you simpler examples to help you understand

Do you understand why that's the answer?

yes I do

it's because one of the functions is defined for x greater than or equal to 0 and the other is only defined for x less than or equal to 9

Right on. Glad you got it.