Question

which function represents exponential decay?
○ a) $y = -8x$
○ b) $y = 0.5x^2$
○ c) $y = -3(1.5)^x$
○ d) $y = 3(0.5)^x$

Explanation:

An exponential decay function has the form $y = ab^x$ where $a
eq 0$ and $0 < b < 1$.

• Option A is linear, not exponential.
• Option B is quadratic, not exponential.
• Option C has $b=1.5>1$, so it is exponential growth.
• Option D has $a=3$ and $b=0.5$ (which is between 0 and 1), so it fits exponential decay.

Answer:

D) $y = 3(0.5)^x$