Given f′(x)=g(x)f'(x) = g(x)f′(x)=g(x) and g′(x)=−f(x)g'(x) = -f(x)g′(x)=−f(x). What is the 4th derivative f(4)(x)f^{(4)}(x)f(4)(x)?
f(x)f(x)f(x)
−f(x)-f(x)−f(x)
g(x)g(x)g(x)
−g(x)-g(x)−g(x)