Engineering Board Exam Reviewer · Binomial Theorem · medium

Find the term independent of x in the expansion of ≤ft(2x2- 1x )9.

  1. -672
  2. 672
  3. 84
  4. 1344

Answer

B. 672

Solution

The general term is 9r(2x2)9-r≤ft(- 1x )r, with exponent of x equal to 2(9-r)-r=18-3r. Setting 18-3r=0 gives r=6: 96(2)3(-1)6=84(8)=672.

More Binomial Theorem questions

  1. Find the constant term in the expansion of ≤ft(x+ 1x )10.
  2. Find the coefficient of x5 in the expansion of (2x-1)8.
  3. Find the 4th term in the expansion of (x+y)6.
  4. Find the coefficient of x3 in the expansion of (1+x)4(1-x)2.
  5. The coefficients of the 2nd, 3rd, and 4th terms in the expansion of (1+x)n are in arithmetic progression. Find n (with n≥3).
  6. Using the first three terms of the binomial expansion, approximate (1.02)10.
  7. Find the sum of the coefficients in the expansion of (3x-2)6.

All Binomial Theorem questions