• find the coefficient of x40 in the expansion of (1/x2 + x4)18
  • find 1st 4 terms in the expansion of ( 1 –x )-1/4
  • show that there is no constant in the exoansion of (2x – x2/4)9
  • using binomial theorem find the value of (9.9)3

find the coefficient of x40 in the expansion of (1/x2 + x4)18

SOLUTION:

 Let (r + 1)th term contains x40 in the binomial expansion of 

 

Now, 

For the coefficient of  x40 ,

-36+6r=40

⇒6r = 40+36=76

 r = 38/3, 

which is impossible.

Thus, there is no term involving x40 in  .


Find the value of (9.9)3

SOLUTION:


Show that there is no constant in the expansion of

 

SOLUTION:

By using general term of the binomial theorem, 

Now, the exponent of x = 0


Thus, there is no constant in the given expansion as the r has negative value

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