[GMAT math practice question]
When f(x)=x^3+1/x3, which of the following is equal to f(-1/x)?
A. f(x)
B. -f(x)
C. 1/f(x)
D. 1-f(x)
E. (f(x))^3
When f(x)=x^3+1/x3, which of the following is equal to f(-1/
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- Max@Math Revolution
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Your Answer
A
B
C
D
E
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GIVEN: f(x)=x³ + 1/x³Max@Math Revolution wrote:[GMAT math practice question]
When f(x)=x³ + 1/x³, which of the following is equal to f(-1/x)?
A. f(x)
B. -f(x)
C. 1/f(x)
D. 1-f(x)
E. (f(x))^3
So, f(-1/x) = (-1/x)³ + 1/(-1/x)³
= -1/x³ + 1/(-1/x³)
= -1/x³ - x³
= -(1/x³ + x³)
= -(x³ + 1/x³)
= -f(x)
Answer: B
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Brent
- Max@Math Revolution
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=>
f(-1/x) = (-1/x)^3 + 1/{1/(-1/x)^3} = -1/x^3 - x^3 = -(x^3+1/x^3) = -f(x).
Therefore, B is the answer.
Answer: B
f(-1/x) = (-1/x)^3 + 1/{1/(-1/x)^3} = -1/x^3 - x^3 = -(x^3+1/x^3) = -f(x).
Therefore, B is the answer.
Answer: B
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