If P(n, r)=2520 and C (n, r)=21 , then what is the value of C (n+1, r+1) ?

Step-by-step solution

aligned & ^n P_r=2520 ; ^n C_r=21 & ^n P_r= n! (n-r)! =2520 aligned ...(1) ^n C_r=- n! (n-r)!. r! =21 ...(2) Divide (1) by (2) aligned & r!= 2520 21 =120 & r!=5! & r=5 & ^n C_r=21 & ^n C₅=21 & n=7 & C(n+1, r+1) & =C(8,6) & = ^8 C₆=28 aligned