Complete the following items. For multiple choice items, write the letter of the correct response on your paper. For all other items, show or explain your work.Let f(x)=x³-4 x²+9 x and let g(x)=6 x³+x²-5 x-12 . What is f(x)-g(x) ?
a. -5 x³-5 x²+14 x+12
b. -5 x³-3 x²+4 x-12
c. 7 x³-3 x²+4 x-12
d. -5 x⁴-5 x³+14 x²+12 x