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function+algebra

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function+algebra

by ska7945 » Mon Aug 11, 2008 1:57 am
12) f(x)=-1/x, f(a)=-1/2, f(ab)=1/6 then what is B?

13)f(k)=(k^5)/16, what is f(2k) in terms of f(k)?

14) which are true when k=-1.
1)k^k=k
2)lkl=-k
3)k^0=-k

provide explanation please.

answer:
[spoiler]-3, 32f(x), i think the answer for last one is everything.[/spoiler]
let's beat GMAT.
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by pepeprepa » Mon Aug 11, 2008 2:51 am
12) f(x)=-1/x, f(a)=-1/2, f(ab)=1/6 then what is B?
a=2
f(2b)=1/6
f(x)=-1/x
Then with b=-3
f(-6)=-1/-6=1/6=f(2b)

13)f(k)=(k^5)/16, what is f(2k) in terms of f(k)?
f(2k)=(2k)^5/16=2^5 * (k^5)/16=2^5*f(k)

14) which are true when k=-1.
1)k^k=k
2)lkl=-k
3)k^0=-k
All of them are true, you reimplace k by -1
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by warlock » Mon Aug 11, 2008 2:51 am
according to me the answers are...

12) f(x)=-1/x, f(a)=-1/2, f(ab)=1/6 then what is B?

answer:

f(ab) = -1/(ab)

f(a) = -1/a ; f(b) = -1/b ; therefore f(a)f(b) = 1/(ab) = -f(ab)
therefore
(-1/2)(f(b)) = - 1/6

therefore f(b) = 1/3.
if you are asking b? then f(b) = -1/b =1/3. therefore b = -3.

13)f(k)=(k^5)/16, what is f(2k) in terms of f(k)?
answer:

f(2k) = [(2k)^5]/16 = (2^5 * k^5)/16 = 32* (k^5/16) = 32f(k)


14) which are true when k=-1.
1)k^k=k
2)lkl=-k
3)k^0=-k

answer: (-1)^(-1) = 1/(-1) = -1 = k. so true.
|-1| = 1 = -k. so true.
-1^0 = 1 = -k. so true.
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