On the function machine shown below, the function rule is given as a variable expression. When the output is 99, what is the input? * a 20

b 9

c 100

d 10

option d.

Step-by-step explanation:

We have the function:

y = f(x) = x^2  - 1

The output is 99 when y = 99, and the input is x.

Then we need to solve:

y = 99 = x^2 - 1

for x.

99 = x^2 - 1

99 + 1  =x^2

100 = x^2

√100 = x

10 = x

The correct option is d, input equals 10.

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step-by-step explanation:

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