SOLUTION: Please help me. find the domain of each function in interval form: 6sqrt(-4+5x) (which reads the 6th root of -4+5x) 5sqrt(-4+5x) (which reads the 5th root of -4+5x)

Algebra ->  Rational-functions -> SOLUTION: Please help me. find the domain of each function in interval form: 6sqrt(-4+5x) (which reads the 6th root of -4+5x) 5sqrt(-4+5x) (which reads the 5th root of -4+5x)      Log On


   

Question 917518: Please help me.
find the domain of each function in interval form:
6sqrt(-4+5x)
(which reads the 6th root of -4+5x)
5sqrt(-4+5x)
(which reads the 5th root of -4+5x)
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
OOPS!
I reversed the numbers.
What's inside the root is
-4%2B5x=5x-4 so for the 6th root to exist we need
5x-4%3E=0---->x%3E=4%2F5
So the interval is
[4/5,infinity).

For the fifth root the answer is still right.

OLD, WRONG ANSWER:
root%286%2C-4x%2B5%29 , being an even index root (6 is an even number),
is defined only when what's inside the root is positive or zero,
meaning -4x%2B5%3E=0<--->5%3E=4x<--->5%2F4%3E=x ,
so the domain is %22%28%22-infinity%22%2C%225%2F4%22%5D%22 .

root%285%2C-4x%2B5%29 , being an odd index root (5 is an odd number),
exists no matter what value -4x%2B5 takes,
so the domain is %22%28%22-infinity%22%2C%22infinity%22%29%22 .