math
posted by Caroline .
functions
f(x)=rad. x9
write the intervals of the functions. How do I put the set of numbers in the form of intervals such as infinity.
I solved it and got the answer as this:
x < or = 9
(infinity,9]
Please help me, I am stuck.

(infinity,9]
means the interval's lower limit is at but excludes ∞. The exclusion is signified by the left parenthesis "(".
The upper limit is 9, and 9 is included, as indicated by the square bracker "]".
I do not quite understand the meaning of
f(x)=rad. x9
so I cannot comment on whether the answer is correct.