Question

In the expansion of (1 + x)10 the
coefficient of (2r + 1)th term is
equal to the coefficient of (4r + 5) th
term then r=​

Answer 1

Answer:

In the expansion of (1+x) 18

coefficient of T2r+4

= 18C2r+3

coefficient of Tr−2

= 18Cr−3

Given,

18C 2r+3

= 18C r−3

⇒2r−3=r+3 or 2r+3+r−3=18

⇒r=−6 or 3r=18⇒r=6

but r cannot be negative

∴r=6

Step-by-step explanation:

DONE ABOVE