Explain, in complete sentences, how you would factor 3x4 – 9x3 – 120x2.

Question

anonymous · Answer

first you want to simplify the equation by factoring $$3x^2$$
this reduces the equation to:
$$3x^2(x^2-3x-40)$$

next you want to factor the second equation, find two numbers that when multiplied together equal -40, and when added together equal -3 (think of the factors of 40)
those two numbers are -8 and 5, so put those numbers into the equation to see it better visually:
$$x^2-8x+5x-40$$
notice i just separated -3x into those two terms, so now you know what factor is:

(x-8)(x+5)
don't forget the $$3x^2$$ though. the final answer is:

$$3x^2[(x-8)(x+5)]$$