JEE Main 2020 — Binomial Theorem Question with Solution
From: JEE Main 2020 (Online) 7th January Evening Slot
Question
The coefficient of x7
in the expression
(1 + x)10 + x(1 + x)9 + x2(1 + x)8 + ......+ x10 is:
(1 + x)10 + x(1 + x)9 + x2(1 + x)8 + ......+ x10 is:
Choose an option
Show full solutionCorrect option: B
Correct answer
B330
Step-by-step explanation
(1 + x)10 + x(1 + x)9
+ x2(1 + x)8
+ ......+ x10
This is a G.P where
First term, a = (1 + x)10
common ratio, r =
Number of terms = 11
Sum of G.P
=
= (1 + x)11 – x11
So Coefficient of x7 is 11C7 = 330
This is a G.P where
First term, a = (1 + x)10
common ratio, r =
Number of terms = 11
Sum of G.P
=
= (1 + x)11 – x11
So Coefficient of x7 is 11C7 = 330
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This is a previous-year question from JEE Main 2020, covering the Binomial Theorem chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.