Question

For the problems: f(x)=(x+4)/(x-5) and f(x)=(4x-5)/(x^2 -10x+21) find the intervals where f(x)>0

Answer 1

I think that it is 7 is less than or equal to x which is less than or equal to 25

Answer 2

but I'm not sure...

Answer 3

The denominator and numerator need to both positive or both negative for positive f(x).

Also try to sketch the graph in order to assist with the thinking.