The function f(x)=x+81+x−81+8−x1 is undefined when any of the denominators are zero. The first denominator, x+8, is zero when x=−8. The second denominator, x−8, is zero when x=8. The third denominator, 8−x, is zero when x=8. Therefore, the function is undefined when x=−8 or x=8.
We also need to consider the restrictions imposed by the square root functions. The square root of a number is undefined when the number is negative. Therefore, the second denominator, x−8, is undefined when x−8<0, which is when x<8. Similarly, the third denominator, 8−x, is undefined when 8−x<0, which is when x>8.
Putting all of this together, the function f(x) is undefined when x=−8, x=8, x<8, or x>8. Therefore, the domain of f(x) is the union of the intervals (−∞,−8)∪(8,∞).
