The function f is defined for all real numbers x as f(x)=x2−1. What is

Question

The function f is defined for all real numbers x as f(x) = x^2 − 1. What is f(f(3))?

A. 26
B. 47
C. 63
D. 75
E. 80

SonalSinha803 · Answer

f(3) = 3^2 - 1 = 8

f(f(3) = f(8) = 8^2 - 1 = 63

Option C.

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pushpitkc · Answer

Given:   f(x) =  x^2 - 1

f(f(x)) = f( x^2 - 1 ) =  (x^2 - 1)^2 - 1 = x^4 - 2x^2 + 1 - 1 = x^4 - 2x^2

Therefore,  f(f(3)) = 3^4 - 2*3^2 = 81 - 18  =  63(Option C)

getahead · Answer

We can break x^2-1 =  
So f(3)= 4x2=8

And F(f(3))=f(8) = (8+1) (8-1) = 63

Option C :63

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ScottTargetTestPrep · Answer

f(3) = 3^2 - 1 = 8

f(f(3)) = f(8) = 8^2 - 1 = 63

So f(f(3)) = 63.

Answer: C

Kinshook · Answer

Given: The function f is defined for all real numbers x as f(x) = x^2 − 1. 
Asked: What is f(f(3))?

f(3) = 3ˆ2 - 1 = 9 -1 = 8
f(f(3)) = f(8) = 8ˆ2 - 1 = 64 -1 = 63

IMO C

MathRevolution · Answer

f(x)=  x^2  - 1

'x' gets mapped as  x^2  -1.

If x = 3, then it gets mapped as  3^2  - 1 = 9 - 1 = 8

Then x = 8, gets mapped as  8^2  - 1 = 64 - 1 = 63

Hence, f(f(3)) = 63

Answer C

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