Consider the following statements -

If n is a prime number such that ( n + 2 ) is also a prime number, then

S1 : { n ( n + 2 ) + 1} is a perfect square.

S2 : ( 2n + 2 ) is divisible by 6 if n is greater than 3.

Which of the statements given above is/are correct?

  1.  Only S1 is correct.
  2. Only S2 is correct.
  3.  Both S1 and S2 are correct.
  4. Both S1 and S2 are incorrect

Answer (Detailed Solution Below)

Option 3 :  Both S1 and S2 are correct.

Detailed Solution

Download Solution PDF

The Correct answer is Option 3. 

Key Points

Considering statement -1:

If n = 3, then (n + 2) = 5

∴ 3 × 5 + 1 = 16, which is a perfect square.

Same is true for n = 5, 11, 17, 29, 41.

So, S1 is true.

Considering statement -2:

If n = 5, then n + 2 = 7 and 5, 7 are both prime numbers.

Now, (2n + 2) = 10 + 2 = 12 and it is divisible by 6.

Same is true for n = 11, 17, 29, 41.

So, statement 2 is also true.

Thus, both S1 and S2 are correct.

Hence, option (c) is correct.

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