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i have a domain question?
find the domain of the following function:
sqrt ((4x)/(x^2-400))
1 Answer
- 1 decade ago
The domain is what ever numbers will make the function work. In this case, sqrt must be greater than 0, nad the denominator can not be 0.
So, start with the denominator. It factors (x+20)(x-20) so x can not be -20 or 20.
Also the fraction must be positive so lets look at some situations:
if x<-20, the numerator is negative, but the denom is positive so that will not work.
If -20<x<0 both the numerator and denominator are negative, giving you a positive fraction
If 0 < x < 20 the numerator is positive, but the denom is negative so that will not work
If x > 20 the whole fraction is positive
so, D = {x| -20<x<0 or x>20}