JEE Main202122 Jul 2021Morning ShiftMathematicsBinomial TheoremActual
The number of elements in the set n ∈ 1 , 2 , 3 , … , 100 ∣ ( 11 ) n > ( 10 ) n + ( 9 ) n is ___________.
Correct answer
0
Step-by-step solution
We have to check 11 n > 10 n + 9 n ⇒ 11 n - 9 n > 10 n ⇒ ( 10 + 1 ) n - ( 10 - 1 ) n > 10 n Using a + b n - a - b n = 2 C 1 n · a n - 1 · b + C 3 n · a n - 3 · b 3 + C 5 n · a n - 5 · b 5 + . . . ⇒ 2 C 1 n · 10 n - 1 + C 3 n · 10 n - 3 + C 5 n · 10 n - 5 + ⋯ ⋯ > 10 n ⇒ 2 n · 10 n - 1 + 2 C 3 n · 10 n - 3 + C 5 n · 10 n - 5 + ⋯ ⋯ > 10 n … 1 For n = 5 , the L . H . S . is 2 · 5 &#