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GATE Aptitude

Aptitude

2)If pq = 28 where p and q (p > q) are whole numbers then which of the following can be (p2 – q2)?

  a)32
 b)83
 c)783
 d)63

 Ans.  p and q can be written in the pairs of (28,1) or (7,4) or (14,2)
We have 142 – 22 = 196 – 4 = 192
       Also, 72 – 42 = 49 – 16 = 33
       Also, 282 – 12 = 784 – 1 = 783
       Hence,  p2 – q2 = 783

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