Question

Which function is increasing?? :)

Answer 1

Answer:

$\large\boxed{B.\ f(x)=4^x}$

Step-by-step explanation:

Exponential function $f(x)=(a)^x$ is

increasing if $a > 1\to a\in(1,\ \infty)$

decreasing if $0 < a < 1\to a\in(0,\ 1)$

$A.\ f(x)=\left(\dfrac{1}{4}\right)^x\to a=\dfrac{1}{4}\in(0,\ 1)\to\text{decreasing}\\\\B.\ f(x)=4^x\to a=4\in(1,\ \infty)\to\text{increasing}\\\\C.\ f(x)=(0.4)^x\to a=0.4\in(0,\ 1)\to\text{decreasing}\\\\D.\ f(x)=\left(\dfrac{1}{2}\right)^x\to a=\dfrac{1}{2}\in(0,\ 1)\to\text{decreasing}$