Question

if 22pr+1:20pr+2=11:52 then find r

Answer 1

Thank you for asking this question:

22pr + 1 : 20pr +2 = 11:52

= 22!/(22-r-1)!/20!/(20-r-2)! = 11/52

= 22! x (18-r)!/20! x (21-r) ! = 11/52

= 22 x 21 x 20! x (18-r)!/20! x (21-r)(20-r)(19-r) x (18-r)! = 11/52

= 22 x 21 / (21-r)(20-r)(19-r)  = 11/52

= (21-r)(20-r)(19-r) = 2 x 21 x 52

= (21-r)(20-r)(19-r) = 2 x 3 x 7 x 4 x 13

= (21-r)(20-r)(19-r) = 14 x 13 x 12

= (21-r)(20-r)(19-r) = (21-7) x (20-7) x (19-7)

r = 7

Answer 2

I hope it'll help you