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# If ∆ x = x for x ≥ 0 and 2x for x < 0,

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Senior RC Moderator
Joined: 02 Nov 2016
Posts: 4942
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If ∆ x = x for x ≥ 0 and 2x for x < 0,  [#permalink]

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17 Feb 2017, 22:20
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84% (00:55) correct 16% (01:22) wrong based on 93 sessions

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If ∆ x = x for x ≥ 0 and 2x for x < 0, $$\frac{∆30}{∆(-5)}$$

A. −12
B. −6
C. −3
D. 6
E. 30

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Joined: 28 May 2014
Posts: 510
GMAT 1: 730 Q49 V41
Re: If ∆ x = x for x ≥ 0 and 2x for x < 0,  [#permalink]

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18 Feb 2017, 02:45
1
∆ x = x for x ≥ 0; Therefore, ∆30 = 30;
Again,
∆ x = 2x for x < 0; Therefore, ∆ (-5) = -10;

so, ∆30/∆ (-5) = 30/(-10) = -3;

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Posts: 4236
Re: If ∆ x = x for x ≥ 0 and 2x for x < 0,  [#permalink]

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18 Feb 2017, 08:47
2
Top Contributor
If ∆x = x for x ≥ 0 and 2x for x < 0, $$\frac{∆30}{∆(-5)}$$

A. −12
B. −6
C. −3
D. 6
E. 30

∆x = x for x ≥ 0
In other words, IF x is greater than or equal to 0, then ∆x = x
So, for example, ∆5 = 5, and ∆11 = 11, and ∆0 = 0, since 5, 11 and 0 are all greater than or equal to 0
Likewise, ∆30 = 30

∆x = 2x for x < 0
In other words, IF x is less than 0, then ∆x = 2x
So, for example, ∆(-3) = 2(-3) = -6, and ∆(-1) = 2(-1) = -2, and ∆(-9) = 2(-9) = -18, since -3, -1 and -9 are all less than 0
Likewise, ∆(-5) = 2(-5) = -10

So....
∆30/∆(-5) = 30/(-10) = -3

Cheers,
Brent
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Re: If ∆ x = x for x ≥ 0 and 2x for x < 0,  [#permalink]

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13 May 2019, 04:30
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Re: If ∆ x = x for x ≥ 0 and 2x for x < 0,   [#permalink] 13 May 2019, 04:30
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