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If R^a*R^b*R^c=R^-9. if R>0 and a,b and c are each different negative

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If R^a*R^b*R^c=R^-9. if R>0 and a,b and c are each different negative  [#permalink]

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New post 19 Nov 2017, 11:17
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If \(R^a*R^b*R^c=R^{-9}\) and if R>0 and a,b and c are each different negative integers, what is the smallest that c could be?
A) -1
B) -2
C) -6
D) -7
E) Cannot be determined

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If R^a*R^b*R^c=R^-9. if R>0 and a,b and c are each different negative  [#permalink]

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New post 19 Nov 2017, 12:03
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souvonik2k wrote:
If \(R^a*R^b*R^c=R^{-9}\) and if R>0 and a,b and c are each different negative integers, what is the smallest that c could be?
A) -1
B) -2
C) -6
D) -7
E) Cannot be determined


\(R^{a+b+c}=R^{-9}\)

\(=>a+b+c=-9\)

so \(c=-9-a-b\). for \(c\) to be smallest either of \(a\) or \(b\) has to be \(-1\) and the other \(-2\)

hence \(c=-9+1+2=-6\)

Option C
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If R^a*R^b*R^c=R^-9. if R>0 and a,b and c are each different negative  [#permalink]

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New post 19 Nov 2017, 12:28
souvonik2k wrote:
If and if R>0 and a,b and c are each different negative integers, what is the smallest that c could be?
A) -1
B) -2
C) -6
D) -7
E) Cannot be determined


\(R^a*R^b*R^c=R^{-9}\)
\(R^{a+b+c} = R^{-9}\)
From the above equation, a+b+c = -9

It has been given that a,b,and c are all negative integers(different)

The largest negative integer is -1, second largest is -2
Hence, the third largest/smallest integer(c) must be -1 + (-2) + c = -9

Therefore, c = -9 + 3 = -6(Option C)
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If R^a*R^b*R^c=R^-9. if R>0 and a,b and c are each different negative  [#permalink]

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New post 19 Nov 2017, 12:30
souvonik2k wrote:
If \(R^a*R^b*R^c=R^{-9}\) and if R>0 and a,b and c are each different negative integers, what is the smallest that c could be?
A) -1
B) -2
C) -6
D) -7
E) Cannot be determined

The trap in this question is "smallest."

It almost got me; I decided that "-1" was too obvious. The smallest negative variable/ number is the one most to the left on the number line.

When bases are the same (here, R), add exponents. Sum = -9

a + b + c = -9
c = 9 - a - b

a and b are different negative integers. To minimize c, to make it farthest to the left of 0, maximize a and b -- make them, going left from zero, as close to 0 as possible.
a = -1
b = -2

c = 9 - a - b
c = 9 - (-1) - (-2) = (-9 + 1 + 2) = -6

Answer C
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If R^a*R^b*R^c=R^-9. if R>0 and a,b and c are each different negative &nbs [#permalink] 19 Nov 2017, 12:30
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