Question

Which of the following functions represent exponential decay? f(x)=3(1.7)^x-2

f(x)=3(1.7)^-2x
F(x)=3^5(1/4)^x
F(x)=3^5(2)^-x

Answer 1

F(x)=3^5(1/4)^x

Explanation:

By the exponential decay definition: y = ab×

b determines the rate at which the graph grows: if b > 1, the function will increase. if 0 < b < 1, the function will decrease.

There is only (1/4)ˣ : where 0<1/4<1 fit the definition, so F(x)=3^5(1/4)^x is the choice

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But.. look at the table attached, the f(x)=3(1.7)^-2x and F(x)=3^5(2)^-x also showed pattern of decay. It can verified from their graphs. (Try plot it with your calculator)

Answer 2

B, C, D

Explanation: