Fill in the blanks:
If `"^(n)P_r = 720` and `"^(n)C_r = 120`, then r = __________

Similar Questions

Explore conceptually related problems

If "^(n-1)C_r : ^nC_r : ^(n+1)C_r= 6:9: 13 , find n and r.

if .^(2n)C_(2):^(n)C_(2)=9:2 and .^(n)C_(r)=10 , then r is equal to

Fill in the Blanks: If R_1 and R_2 are two congruent regions, then area of R_1 is ______ are of R_2

Find the sum sum_(r=0)^n^(n+r)C_r .

Prove that "^nC_r+2 ^(n)C_(r-1)+ ^(n)C_(r-2) = ^(n+2)C_r .

Evaluate (n!)/(r!(n - r)! , when n = 10 , r = 2

If ^n P_r=^n P_(r+1)a n d^n C_r=^n C_(r-1,) then the value of n+r is.

If .^(n)C_(r )=84, .^(n)C_(r-1)=36 " and" .^(n)C_(r+1)=126 , then find the value of n.

Prove that: sum_(r=0)^(n) 3^( r) ""^(n)C_(r) = 4^(n) .