Question

Se f(x) = 4^x, então f(x + 1) - f(x) é igual a:

a) 4 d) 3f(x)
b) f(x) e) 4f(x)
c) 2f(x)

Answer 1

$f(x)=4^x\qquad\qquad\qquad\qquad{f}(x+1)-f(x)=\ ?\\\\\\f(x+1)=4^{(x+1)}\\\\f(x+1)=4^x\cdot4^1\\\\\therefore{f}(x+1)=f(x)\cdot4\\\\f(x+1)=4f(x)\\\\\\f(x+1)-f(x)=\ ?\\\\4f(x)-f(x)=\boxed{3f(x)}\\\\\\\text{Alternativa d).}$