Question

Please help me get the right answer?!

What is the value of f(x) =9^x when x=-2

A. 1/81

B.81

C.1/18

D.18

Answer 1

Hi!

Let's put the value of x into the equation.

f(-2) =
`9^(-2)`
solve
f(-2) = 0.012345679

Now let's see if this is equal to any of the answers.

1/81 = 0.012345679 correct
81 = 0.012345679 wrong
1/18 = 0.012345679 wrong
18 = 0.012345679 wrong

The answer is A. 1/81

Hope this helps! :)

Answer 2

The answer is A,
`(1)/(81)`. This is because when plugging in -2 for x, the expression will look like this:
`9^(-2)`. To make the exponent positive, you have to flip it into a fraction. Then it will be
`(1)/(9^2)`. Lastly, you simplify the denominator into 81.