We can try factoring by grouping:
Group the first two terms and the last two terms:
$$5[(x^3 + 2x^2) + (-4x - 8)]$$
Factor out the GCF from each group:
$$5[x^2(x + 2) - 4(x + 2)]$$
Now, we can see that both terms have a common factor of $(x + 2)$. We can factor
Show more…