The coefficient of x 5 in the expansion of 2 x 3 - 1 3 x 2 5 is

The coefficient of x5 in the expansion of 2x3-13x25 is 
  1. 809
  2. 9
  3. 8
  4. 263

Solution

General term of the binomial expansion of 2x3-13x25 is

Tr+1=5Cr(2x3)5-r -13x2r

Tr+1=Cr525-r-13rx15-5r

For coefficient of x5, we must have

15-5r=5r=2

So, required coefficient is

=C25(2)319=10×8×19=809

Asked in: JEE Main 2023 (13 Apr Shift 2)

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