I'm studying for the AP exam and I can't figure this problem out.

I thought the answer was negative infinity but that isn't an option. Thank you in advance!

What is the limit as x approaches infinity of (9x-x^2-7x^4)/(x^3+12x)?
a. 9
b. 7
c. -7/12
d. -7
e. Does not exist

since the power of the numerator is one degree higher than that of the denominator we get

y = (9x-x^2-7x^4)/(x^3+12x) = -7x + ??

so as x gets bigger, y gets bigger, so the limit is undefined, (approaches negative infinity, or we can say the limit does not exist