Exams Joint Entrance Examination Mathematics Binomial Theorem Question 35 Question 35 of 347 Medium MCQ
If the constant term in the expansion of ( 53 x + ) 12 , x ≠ 0 {(\frac{\sqrt{53}}{}x}^{+})12,x\ne 0 ( 53 x + ) 12 , x = 0 , is α × 2 8 × 53 \alpha \times {2}^{8}\times \sqrt{53} α × 2 8 × 53 , then 25 α 25\alpha 25 α is equal to :
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( 53 x + ) 12 T r + 1 = 12 C r ( 53 x ) 12 − r ( 2 x 35 ) r \begin{gathered} {(\frac{\sqrt{53}}{}x}^{+})12 \end{gathered}{T}_{r+1}={}^{12}Cr{(\frac{\sqrt{53}}{}x}^{)}12-r{(\frac{2x}{\sqrt{35}}}^{)}r ( 53 x + ) 12 T r + 1 = 12 C r ( 53 x ) 12 − r ( 35 2 x ) r
For constant term − 12 + r + r = 0 -12+r+r=0 − 12 + r + r = 0
⇒ r = 6 ∴ = 12 C 6 ( 3 ) 6 5 ( 5 ) 6 3 ( 2 ) 6 \begin{gathered} \Rightarrow \, r=6 \\ \therefore \, ={}^{12}{C}_{6}\frac{(3{)}^{\frac{6}{5}}}{(5{)}^{\frac{6}{3}}}(2{)}^{6} \end{gathered} ⇒ r = 6 ∴ = 12 C 6 ( 5 ) 3 6 ( 3 ) 5 6 ( 2 ) 6
= 12 C 6 × 2 6 25 × 3.3 1 5 = 231 25 × 2 8 ⋅ 3 1 5 ⋅ 3 = 693 25 ⋅ 2 8 53 ∴ α = 693 25 25 α = 693 \begin{gathered} ={}^{12}{C}_{6}\times \frac{{2}^{6}}{25}\times {3.3}^{\frac{1}{5}} \\ =\frac{231}{25}\times {2}^{8}\cdot {3}^{\frac{1}{5}}\cdot 3 \\ =\frac{693}{25}\cdot {2}^{8}\sqrt{53} \end{gathered}\therefore \, \alpha =\frac{693}{25}25\alpha =693 = 12 C 6 × 25 2 6 × 3.3 5 1 = 25 231 × 2 8 ⋅ 3 5 1 ⋅ 3 = 25 693 ⋅ 2 8 53 ∴ α = 25 693 25 α = 693 Answer the question to unlock