Q32 of 70 Page 371

Show that the expansion of does not contain any term involving x⁹.

For ,

a=2x², and n=20

We have a formula,

To get coefficient of x⁹ we must have,

(x)^40-3r = (x)⁹

• 40 - 3r = 9

• 3r = 31

• r = 10.3333

As is not possible

Therefore, the term containing x⁹ does not exist in the expansion of

Find the coefficient of

(i)x⁵ in the expansion of (x + 3)⁸

(ii) x⁶ in the expansion of .

(iii) x^-15 in the expansion of .

(iv) a⁷b⁵ in the expansion of (a – 2b)¹².

Show that the term containing x³ does not exist in the expansion of .

Show that the expansion of does not contain any term involving x^-1.

Write the general term in the expansion of

(x² – y)⁶

Show that the expansion of does not contain any term involving x9.