The number of terms in the expansion of (1 + 2x + x2)20 when expanded in descending powers of x, is

Question

The number of terms in the expansion of (1 + 2x + x2)20 when expanded in descending powers of x, is (A) 20 (B) 21 (C) 40 (D) 41

Tardigrade Admin · Accepted Answer

We have (1 + 2x + x2)20 = ((1 + x)2)20 = (1 + x)40 ∴ total no. of terms in the expansion = 40 + 1=41

Q. The number of terms in the expansion of $(1 + 2 x + x^{2})^{20}$ when expanded in descending powers of x, is