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Q41 (CISF/2018) Science & Technology › Basic Science (Physics, Chemistry, Biology)

The difference of squares of two consecutive odd numbers is always

Explanation

Let the two consecutive odd numbers be represented as (2n - 1) and (2n + 1), where n is an integer. To find the difference of their squares, we calculate:

(2n + 1)2 - (2n - 1)2

Using the algebraic identity a2 - b2 = (a - b)(a + b):

  • a = 2n + 1
  • b = 2n - 1
  • (a - b) = (2n + 1) - (2n - 1) = 2
  • (a + b) = (2n + 1) + (2n - 1) = 4n

The difference is 2 × 4n = 8n. Since n is an integer, the result 8n is always a multiple of 8, meaning it is always divisible by 8. For example, 32 - 12 = 8 and 52 - 32 = 16; both are divisible by 8. However, since 8 is not divisible by 16 or 3, those options are not universally true.

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