For the inside argument, the domain is all real numbers except where the denominator is zero.
If your denominator is
-x^2-4x-10
it is never zero, since the discriminant is 16-40 < 0
So, the domain is (-∞,∞)
Now, for the log to be defined, we need
10+|x+6|/(-x^2-4x-10) > 0
|x+6|/(-x^2-4x-10) > -10
It should not take you too long to see that this is always true.
So, the domain of the entire function is (-∞,∞)
The graph confirms this at
http://www.wolframalpha.com/input/?i=10%2B%7Cx%2B6%7C%2F(-x%5E2-4x-10)+for+-10+%3C%3D+x+%3C%3D+10
log (10+|x+6|/-x^2-4x-10) find the domain
-x^2-4x (-2)^2>10
x>-2+ or -square root 14
10+|x+6|>0
x+6>-10
x>-16
x+6>10
x>4
1 answer
1 answer