Quantative Reasoning: p^2+q^2=25, 2pq=10, find (p-q)^2  TOPIC_SOLVED

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Quantative Reasoning: p^2+q^2=25, 2pq=10, find (p-q)^2

Postby foood on Sat Dec 31, 2011 8:53 am

if p2+q2= 25 and 2pq=10, what is (p-q)2?

a)250
b)100
c)50
d) 5

i dont get this...the answer is b) and i guessed c).
i only know that pq=5 and possible values for the p and q in p2+q2= 25 are p=4 and q=3 or vice versa.
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Re: Quantative Reasoning: p^2+q^2=25, 2pq=10, find (p-q)^2  TOPIC_SOLVED

Postby theshadow on Mon Jan 09, 2012 2:23 pm

i'm surprised nobody answered this. you need to use the perfect squares formula: (p-q)^2 = p^2-2pq+q^2

then p^2+q^2-2pq = 25-10 = 15 = (p-q)^2

i think all the answers are wrong
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