\(g(x)=f\left((x^2 - 2)/(x + 1)\right)\).
We can only input values from -8 to 8 in the function, so let's start from there.
\(-8\le\frac{{x}^{2}-2}{x+1}\le8\)
Consider there two seperately.
Case 1: \(-8\le\frac{{x}^{2}-2}{x+1}\)
\(\frac{{x}^{2}+8x+6}{x+1}\ge0\)
Use the method of intervals, or the wavy curve method. (I love that name
).
\({x}^{2}+8x+6\) has roots at \(-4 \pm \sqrt{10}\).
so we get \(\frac{{x}^{2}+8x+6}{x+1}\ge0\) on the intervals \([-4-\sqrt{10}, -1)\cup[-4+\sqrt{10}, \infty)\). Remember, you can't plug -1 in so thats why it's not included.
Case 2: \(\frac{{x}^{2}-2}{x+1}\le8\). (I will spare some explanation here, its the same as above).
The interval turns out to be \((-\infty, 4-\sqrt{26}]\cup(1, 4+\sqrt{26}]\).
Now, we need to find the intersection of these intervals, since it satisfies both conditions.
We get \([-4-\sqrt{10}, 4-\sqrt{26}]\cup[-4+\sqrt{10}, 4+\sqrt{26}]\).
This interval has a width of 16.