मराठी

The Number of Irrational Terms in the Expansion of ( 4 1 / 5 + 7 1 / 10 ) 45 is (A) 40 (B) 5 (C) 41 (D) None of These

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प्रश्न

The number of irrational terms in the expansion of \[\left( 4^{1/5} + 7^{1/10} \right)^{45}\]  is

 

पर्याय

  •  40

  •  5

  • 41

  • none of these

     
MCQ
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उत्तर

41

\[\text{ The general term } T_{r + 1} \text{ in the given expansion is given by } \]

\[ ^{45}{}{C}_r ( 4^{1/5} )^{45 - r} ( 7^{1/10} )^r \]

\[\text{ For }  T_{r + 1}\text{  to be an integer, we must have }  \frac{r}{5} \text{ and } \frac{r}{10}\text { as integers i . e } . 0 \leq r \leq 45\]

\[ \therefore r = 0, 10, 20, 30 \text{  and }  40\]

\[\text{ Hence, there are 5 rational and 41, i . e . , 46 - 5, irrational terms } .\]

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पाठ 18: Binomial Theorem - Exercise 18.4 [पृष्ठ ४६]

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आर.डी. शर्मा Mathematics [English] Class 11
पाठ 18 Binomial Theorem
Exercise 18.4 | Q 6 | पृष्ठ ४६

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