Given: nCr+1 = nC8 Need to find: Value of 22Cn We know, one of the property of combination is: If nCr = nCt, then, (i) r = t OR (ii) r + t = n We are going to use property (i) nCr+1 = nC8 By the property (i), ⇒ r + 1 = 8 ⇒ r = 7 Now we are going to use property (ii) ⇒ n = 8 + 7 + 1 = 16 Therefore, 22Cn = 22C16 = 74613.

Q. 35.0( 1 Vote )

If ⁿC<

Class 11th RS Aggarwal - Mathematics 9. Combinations

Answer :

Given: ⁿC_r+1 = ⁿC₈ Need to find: Value of ²²C_n We know, one of the property of combination is: If ⁿC_r = ⁿC_t, then, (i) r = t OR (ii) r + t = n We are going to use property (i) ⁿC_r+1 = ⁿC₈ By the property (i), ⇒ r + 1 = 8 ⇒ r = 7 Now we are going to use property (ii) ⇒ n = 8 + 7 + 1 = 16 Therefore, ²²C_n = ²²C₁₆ = 74613.

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