MY CART (5)

Use Coupon: CART20 and get 20% off on all online Study Material

ITEM
DETAILS
MRP
DISCOUNT
FINAL PRICE
Total Price: Rs.

There are no items in this cart.
Continue Shopping
Menu
Grade: 11
        If the coefficient of x3 in the expansion of (1+x)n is 20 find n and n is in power
11 months ago

Answers : (1)

Arun
14889 Points
							
 
Dear Priyansh
 
General term = nCr x^r
Now
x³ coefficient = 20
r = 3
 
Now
nC3 = 20
Hence
n!/3!*(n-3)! = 20
n(n-1)(n-2) = 120
(n²-n)(n-2) = 120
n³ - 3n² +2n -120 = 0
Now find n
 
Regards
Arun (askIITians forum expert)
11 months ago
Think You Can Provide A Better Answer ?
Answer & Earn Cool Goodies

Get Extra Rs. 1,590 off

COUPON CODE: SELF10


Course Features

  • 731 Video Lectures
  • Revision Notes
  • Previous Year Papers
  • Mind Map
  • Study Planner
  • NCERT Solutions
  • Discussion Forum
  • Test paper with Video Solution


Course Features

  • 101 Video Lectures
  • Revision Notes
  • Test paper with Video Solution
  • Mind Map
  • Study Planner
  • NCERT Solutions
  • Discussion Forum
  • Previous Year Exam Questions


Get Extra Rs. 233 off

COUPON CODE: SELF10

Ask Experts

Have any Question? Ask Experts

Post Question

 
 
Answer ‘n’ Earn
Attractive Gift
Vouchers
To Win!!! Click Here for details