Quick Math help PLEASE!

[chapset]

dany612 said:

chapset said:

first answer is 4050

x=90

the second the domaine is (3,infinite)

*it's any number that doesn't give a negative scareroot

what is v-1?? a derivative??

I have updated it, I posted it on Google docs. and the second one is not 3 to infinity. I tried that and got it wrong. I had to solve for x in order to find the domain and it worked. 

so the domain was 2.25, to infinity

 

And thanks for the first one. But how did you do it? I could barely see the graph on my calculator?

my bad i thought you could only use ''whole'' numbers, for the first it's a simple derivative that you equal to 0 this will give you the critic numbers, usually you need to do a second derivative to find if your critic number is a minimum or a maximum but since you only get one answer 90 it's a min and a max at the same time