Question

10C3 + 2(10C4) + 10C5 = 12Cx
find x​

Answer 1

Answer:

x = 7

Step-by-step explanation:

Given in the question

10C3 + 2(10C4) + 10C5 = 12Cx

Combination can be calculated as

nCx = n!/(n-x)! * x!

So 10C3 = 10!/(10-3)!*3! = 120

2*(10C4) = 2*10!/(10-4)!*4! = 420

10C5 = 10!*(10-5)!*5! = 252

so 10C3 + 2(10C4) + 10C5 = 120 + 420 + 252 = 792

12Cx = 792

So x = 7