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JEE Main 20262 AprilEvening Shift
Exam
JEE Main
Year
2026
Date
2 April
Shift
Evening Shift
Subject
Mathematics
Chapter
Binomial Theorem

JEE Main 2026 · 2 April · Evening Shift · Mathematics · Binomial Theorem

If for 3 ≤ r ≤ 30 , 30 30-r + 3 30 31-r + 3 30 32-r + 30 33-r = m r...

If for 3≤r≤303 \leq r \leq 30, (3030−r)+3(3031−r)+3(3032−r)+(3033−r)=(mr)\binom{30}{30-r} + 3\binom{30}{31-r} + 3\binom{30}{32-r} + \binom{30}{33-r} = \binom{m}{r}, then mm equals:

Options

  1. A3131
  2. B3232
  3. C3333
  4. D3434

Correct answer

C. 3333

Step-by-step solution

Using the property nCr=nCn−r^{n}C_{r} = ^{n}C_{n-r}, the given expression can be written as:

30Cr+3⋅30Cr−1+3⋅30Cr−2+30Cr−3^{30}C_{r} + 3 \cdot ^{30}C_{r-1} + 3 \cdot ^{30}C_{r-2} + ^{30}C_{r-3}

This expression represents the coefficient of xrx^r in the expansion of:

(1+x)30+3x(1+x)30+3x2(1+x)30+x3(1+x)30(1+x)^{30} + 3x(1+x)^{30} + 3x^2(1+x)^{30} + x^3(1+x)^{30}

Taking (1+x)30(1+x)^{30} common, we get:

(1+x)30(1+3x+3x2+x3)(1+x)^{30}(1 + 3x + 3x^2 + x^3)

=(1+x)30(1+x)3= (1+x)^{30}(1+x)^3

=(1+x)33= (1+x)^{33}

The coefficient of xrx^r in (1+x)33(1+x)^{33} is 33Cr^{33}C_{r}.

Comparing this with mCr^{m}C_{r}, we get m=33m = 33.

Answer: 3333
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