Question number 16. Please give a shortcut method (if any).

Q16. The continued product of (1 + x) , (1 + x2) , (1 + x4), (1 + x8 ) and ( 1 – x ) is :

         (A) ( 1 – x16 )                         (B) ( x16  – 1)

         (C) ( 1 – x8 + x16)                  (D) ( x8 + x16 )
 

Dear Student,

We use the identity a2 - b2 = (a + b)(a - b) repeatedly to solve the given question.(1 - x)(1 + x)(1 + x2)(1 + x4)(1 + x8) = (1 - x2)(1 + x2)(1 + x4)(1 + x8)                                                                      = (1 - x4)(1 + x4)(1 + x8)                                                                      = (1 - x8)(1 + x8)                                                                      = (1 - x16)

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