Question

If 5pr=6pr-1, find r

Answer 1

HELLO DEAR,



${5}p_{r} = 6p_{r - 1} \\ \\ \frac{5!}{(5 - r)!} = \frac{6!}{6 - (r - 1)} \\ \\ \frac{5!}{(5 - r)!}= \frac{6*5!}{(7 - r)(6 - r)(5 - r)!} \\ \\ (7 - r)(6 - r) = 6 \\ \\ 42 - 7r - 6r + r^{2} = 6 \\ \\ r^{2} - 13r + 36= 0 \\ \\ r^{2} - 9r - 4r + 36 = 0 \\ \\ r(r - 9)- 4(r - 9) = 0 \\ \\ (r - 4)(r - 9) = 0 \\ \\ r = 4 , r = 9$




I HOPE ITS HELP YOU DEAR,
THANKS

Answer 2

Answer:

hope it helps you please mark as brainliest and thank you and follow me