If nC8 = nC2, then n isa)8b)12c)10d)2Correct answer is option 'C'. Can...
Explanation:
To solve this problem, we need to use the formula for the combination (nCr), which is given by:
nCr = n! / (r!(n-r)!)
where n is the total number of objects, and r is the number of objects chosen at a time.
Given that nC8 = nC2, we can set up the equation as follows:
n! / (8!(n-8)!) = n! / (2!(n-2)!)
To simplify the equation, we can cancel out the common terms on both sides:
(n-2)! * 8! = (n-8)! * 2!
Now, let's expand the factorials:
(n-2)! * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1 = (n-8)! * 2 * 1
Cancel out the common terms:
8 * 7 * 6 * 5 * 4 * 3 = (n-8)!
We are left with:
8 * 7 * 6 * 5 * 4 * 3 = (n-8)!
Now, let's evaluate the factorial on the left side:
8 * 7 * 6 * 5 * 4 * 3 = 20160
So, we have:
20160 = (n-8)!
To find the value of n, we need to determine the value of (n-8)!. We can do this by finding the factorial of numbers from 1 to 8 until we find a number that is equal to or greater than 20160.
By evaluating the factorials, we find that 8! = 40320, which is greater than 20160. The next factorial, 7!, is equal to 5040, which is less than 20160.
Therefore, n must be greater than 8 but less than 16. The only option that satisfies this condition is option 'C', which is 10.
Hence, the correct answer is option 'C'.
If nC8 = nC2, then n isa)8b)12c)10d)2Correct answer is option 'C'. Can...
Given nC8 = nC2
if nCr = nCp
Then either r=p or r=n−p
Thus, nC8 = nC2
8=n−2
10=n
∴ n=10