Q.

Sum of the last 20 coefficients in the expansion of (1+x)39 , when expanded  in ascending powers of x, is

see full answer

Talk to JEE/NEET 2025 Toppers - Learn What Actually Works!

Real Strategies. Real People. Real Success Stories - Just 1 call away
An Intiative by Sri Chaitanya

a

219

b

218

c

40C20−219

d

238

answer is D.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

There are 40 terms in the expansion of (1+x)39 :Sum of last 20 coefficients is S=39C20+39C21+…+39C38+39C39⇒S=39C19+39C18+…+39C1+39C0 Adding the above two expansions we get 2S=39C0+39C1+…+39C39=239⇒S=238.
Related Blogs
Get ₹ 1 crore* worth scholarship for JEE / NEET / Foundation
Result Producing online coaching for JEE/NEET of south India
Largest All India Test Series for JEE/NEET
Best Books for IIT JEE
Best Books for NEET
How to Join IIT after 10th
score_test_img

Get Expert Academic Guidance – Connect with a Counselor Today!

Related Blogs
Get ₹ 1 crore* worth scholarship for JEE / NEET / Foundation
Result Producing online coaching for JEE/NEET of south India
Largest All India Test Series for JEE/NEET
Best Books for IIT JEE
Best Books for NEET
How to Join IIT after 10th
whats app icon
Sum of the last 20 coefficients in the expansion of (1+x)39 , when expanded  in ascending powers of x, is