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A couple of Functions questions

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Current Student
Joined: 13 Jul 2009
Posts: 145

Kudos [?]: 389 [0], given: 22

Location: Barcelona
Schools: SSE
A couple of Functions questions [#permalink]

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27 Aug 2009, 03:50
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If $$f(x)$$ is defined as the greatest integer less than $$\frac{x}{7}$$, and $$g(x)$$ is defined as the least integer greater than $$\frac{x}{7}$$, then what is the value of $$f(115) + g(60)$$?

If $$f(x) = x^2 - 7x - 10$$ and $$g(x) = f(x-7)$$, what is the positive root of the equation $$f(x) = g(2)$$?

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Kudos [?]: 389 [0], given: 22

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Joined: 10 Jul 2009
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Kudos [?]: 114 [0], given: 8

Re: A couple of Functions questions [#permalink]

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27 Aug 2009, 06:53
1)
f(115) = 115/7 = 16(3/7) = 16
g(60) = 8(4/7) = 9
So f(115) + g(60) = 25

2) f(x) = x^2 - 7x - 10
g(x) = f(x-7)
f(x) = g(2)
g(2) = f(2-7) = f(-5) = 25 + 35 - 10 = 50
Square root (50) = 5 * square root(2)

Kudos [?]: 114 [0], given: 8

Current Student
Joined: 13 Jul 2009
Posts: 145

Kudos [?]: 389 [0], given: 22

Location: Barcelona
Schools: SSE
Re: A couple of Functions questions [#permalink]

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28 Aug 2009, 02:45
Hi Aleehsgonji, you solved nicely the first, however you misread 'positive root' as 'positive square root'.

$$f(x) = g(2) = 50$$

$$x^2 - 7x - 60 = 0$$

$$(x+5)(x-12)$$

Therefore, the positive root is 12.
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Performance: Gmat | Toefl
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Kudos [?]: 389 [0], given: 22

Re: A couple of Functions questions   [#permalink] 28 Aug 2009, 02:45
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A couple of Functions questions

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