Question:

The number of terms in the expansion of $(\sqrt5+\sqrt[4]11)¹24$ which are integers is equal to ________.

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The number of terms in the expansion of $(\sqrt5+\sqrt[4]11)
Updated On: Apr 15, 2026
  • 0
  • 30
  • 31
  • 32
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The Correct Option is D

Solution and Explanation

Step 1: General Term
$T_{r+1} = {}^{124}C_r (5)^{\frac{124-r}{2}} (11)^{\frac{r}{4}}$.
Step 2: Rationality Condition
For the term to be an integer, both exponents $\frac{124-r}{2}$ and $\frac{r}{4}$ must be integers.
Step 3: Solving for r
$r$ must be a multiple of 4. Since $0 \le r \le 124$, possible values are $0, 4, 8, \dots, 124$.
Step 4: Counting
Number of terms $= \frac{124}{4} + 1 = 31 + 1 = 32$.
Final Answer: (D)
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