f(x)=x^3+4x−7
g(x)=6x^4−5x+2

What is f(x)−g(x)?

f(x)−g(x)=x−x
f(x)−g(x)=−6x^4+x^3+9x−9
f(x)−g(x)=6x^4−x^3−9x+9
f(x)−g(x)=6x^4+x^3−x