A function \(f(x)=b\cdot a^x\) shows
- exponential growth, if \(a>1;\)
- exponential decay, if \(0
Consider all options:
A. The function \(f(x)=0.4\cdot 3^x\) shows exponential growth, because \(3>1.\)
B. The function \(f(x)=3\cdot 0.5^x\) shows exponential decay, because \(0<0.5<1.\)
C. The function \(f(x)=0.8\cdot 0.9^x\) shows exponential decay, because \(0<0.9<1.\)
D. The function \(f(x)=0.9\cdot 5^{-x}=0.9\cdot \left(\dfrac{1}{5}\right)^x\) shows exponential decay, because \(0<\dfrac{1}{5}<1.\)
Answer: correct choice is A
