উত্তর সিলেক্ট করলে সঠিক ও ভুল দেখাবে।
ব্যাখ্যা ও সঠিক সমাধান
উত্তর:
15
Given nC6 = nC5. Using the property nCr = nC(n-r), we have nC6 = nC(n-5). So, 6 = n-5, which means n = 11. Then nC2 = 11C2 = (11 × 10) / (2 × 1) = 55. Note: The provided options in the image seem to have a typo as 55 is not listed, but based on the calculation n=11, 11C₂=55.