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Sub 505 (Easy)|   Exponents|      
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shridhar786
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P = a^4*b^7, where a^2 = 1 and b^2 = 9. What is the value of P? 01 Aug 2019, 12:36
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B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

5% (low)

Question Stats:

78% (00:52) correct 22% (00:58) wrong based on 194 sessions

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\(P = a^4*b^7\), where \(a^2 = 1\) and \(b^2 = 9\). What is the value of P?


(1) a < 0

(2) b < 0
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B
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Staphyk
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P = a^4*b^7, where a^2 = 1 and b^2 = 9. What is the value of P? 01 Aug 2019, 13:36
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Wrong tag it should be sub-600 level i think so
P=a^4•b^7 ,where a^2=1 and b^2=9 What is the value of P?


(1) a < 0
So a= -ve ,no information on b and it can be +ve/-ve
P=(-ve)^4•(+ve)^7 =+ve numbers
However, P=(-ve)^4•(-ve)^7 =-ve number
Not sufficient :(

(2) b < 0
b=-ve,no info. on a can be +ve/-ve
P=(-ve)^4•(-ve)^7=-ve number
Also ,P=(+ve)^4•(-ve)^7=-ve number
Sufficient :)

Smack that B!

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P = a^4*b^7, where a^2 = 1 and b^2 = 9. What is the value of P? 09 Jun 2021, 06:33
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can someone please give a little more clarity on why B is the correct answer.
B will only tell us the sign of the value of P but it does not actually helps us figure out the value of P.
and P= -ve could be any value so like wouldn't statement 2 be insufficient.



please help
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P = a^4*b^7, where a^2 = 1 and b^2 = 9. What is the value of P? 09 Jun 2021, 09:19
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Hadiagh
can someone please give a little more clarity on why B is the correct answer.
B will only tell us the sign of the value of P but it does not actually helps us figure out the value of P.
and P= -ve could be any value so like wouldn't statement 2 be insufficient.



please help
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\(P = a^4*b^7\), where \(a^2 = 1\) and \(b^2 = 9\). What is the value of P?

Since \(a^2 = 1\), then \(a^4=1\);
Since \(b^2 = 9\), then \(b=3\) or \(b=-3\).

Therefore, \(P =3^7\) or \(P=(-3)^7\)

Basically to get the value of P we only need to know whether b is positive or negative.

(1) a < 0. Not sufficient.

(2) b < 0 --> \(b=-3\) --> \(P=(-3)^7\). Sufficient.

Answer: B.
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P = a^4*b^7, where a^2 = 1 and b^2 = 9. What is the value of P? 09 Jun 2021, 09:44
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Given: \(P = a^4*b^7\), where \(a^2 = 1\) and \(b^2 = 9\).
Asked: What is the value of P?

a = 1 or -1
b = 3 or -3

(1) a < 0
a = -1
\(P = a^4*b^7= 1*b^7\)
P = 3^7 or -3^7
NOT SUFFICIENT

(2) b < 0
b = -3
\(P = a^4*b^7= 1*(-3)^7= - 3^7\)
SUFFICIENT

IMO B
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P = a^4*b^7, where a^2 = 1 and b^2 = 9. What is the value of P? 10 Jun 2021, 03:56
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Bunuel
Hadiagh
can someone please give a little more clarity on why B is the correct answer.
B will only tell us the sign of the value of P but it does not actually helps us figure out the value of P.
and P= -ve could be any value so like wouldn't statement 2 be insufficient.



please help


\(P = a^4*b^7\), where \(a^2 = 1\) and \(b^2 = 9\). What is the value of P?

Since \(a^2 = 1\), then \(a^4=1\);
Since \(b^2 = 9\), then \(b=3\) or \(b=-3\).

Therefore, \(P =3^7\) or \(P=(-3)^7\)

Basically to get the value of P we only need to know whether b is positive or negative.

(1) a < 0. Not sufficient.

(2) b < 0 --> \(b=-3\) --> \(P=(-3)^7\). Sufficient.

Answer: B.
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okay yes that helped thankyou...
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