Find the number of terms in the expansion of
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Using the well known identity , x 3 + 1 = ( x + 1 ) ( x 2 − x + 1 ) , ( x + 1 ) 1 0 1 ( x 2 − x + 1 ) 1 0 0 = ( x 3 + 1 ) 1 0 0 ( x + 1 ) = x ( x 3 + 1 ) 1 0 0 + ( x 3 + 1 ) 1 0 0 From the binomial theorem , we have, ( x 3 + 1 ) 1 0 0 = ( 0 1 0 0 ) x 0 + ( 1 1 0 0 ) x 3 + ( 2 1 0 0 ) x 6 + ⋯ + ( 9 9 1 0 0 ) x 2 9 7 + ( 1 0 0 1 0 0 ) x 3 0 0 ⟹ x ( x 3 + 1 ) 1 0 0 = ( 0 1 0 0 ) x 1 + ( 1 1 0 0 ) x 4 + ( 2 1 0 0 ) x 7 + ⋯ + ( 9 9 1 0 0 ) x 2 9 8 + ( 1 0 0 1 0 0 ) x 3 0 1 Observe that ( x 3 + 1 ) 1 0 0 and x ( x 3 + 1 ) 1 0 0 have no common powers of x in their expansion, so their sum cannot be simplified any further (the terms cannot be combined). Both of the above expansions have 1 0 1 terms. Therefore, the total number of terms is 2 0 2