Question

What are the values of f(x) = 9^x when x= -2? a) 1/81 b) 81 c) 1/18 d) 18

Answer 1

Answer:

(a)

Step-by-step explanation:

using the rule of exponents

• $a^{-m}$ ⇔ $\frac{1}{a^{m} }$, hence

$9^{-2}$ = $\frac{1}{9^{2} }$ = $\frac{1}{81}$ → (a)

Answer 2

Answer:

A. 1/81

Step-by-step explanation:

1. f(x)=9^x    (Original problem)
2. x= -2 .      ( Exponent (x) equals to -2)
3. 9^-2         (Plug -2 into x)

Since the exponent is negative, the final answer is a reciprocal and the exponent becomes positive.

4. 1/(9^2)            ( Reciprocal of 9^-2)

= 1/81                  ( Simplify 1/9^2 = 1/9^2)