JEE Main 2020 — Binomial Theorem Question with Solution
From: JEE Main 2020 (Online) 9th January Morning Slot
Question
The coefficient of x4 is the expansion of
(1 + x + x2)10 is _____.
Enter your answer
Show full solutionCorrect answer: 615
Correct answer
615
Step-by-step explanation
(1 + x + x2)10
= 10C0(1 + x)10 + 10C1(1 + x)9.x2 + 10C2(1 + x)8.x4+ .....
Coefficient of x4
= 10C0.10C4 + 10C1.9C2 + 10C2.8C0
= 210 + 360 + 45
= 615
= 10C0(1 + x)10 + 10C1(1 + x)9.x2 + 10C2(1 + x)8.x4+ .....
Coefficient of x4
= 10C0.10C4 + 10C1.9C2 + 10C2.8C0
= 210 + 360 + 45
= 615
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