Binomial Theorem And Its Simple Applications Question 137

Question: The number of distinct terms in the expansion of $ {{( x+\frac{1}{x}+x^{2}+\frac{1}{x^{2}} )}^{15}} $ is/are (with respect to different power of x)

Options:

A) 255

B) 61

C) 127

D) none of these

Show Answer

Answer:

Correct Answer: B

Solution:

  • [b] $ {{( x+\frac{1}{x}+x^{2}+\frac{1}{x^{2}} )}^{15}}={{( \frac{x^{3}+x+x^{4}+1}{x^{2}} )}^{15}} $

$ =\frac{a_0+a_1x+a_2x^{2}+…+a_{60}x^{60}}{x^{30}} $

Hence, the total number of terms is 61.