Question

1) find "n" and "r" , if npr =840, ncr=35 2) if nc3:(n-1) c4=8:5,then find n. ​do the problem please i will give you brain list mark​

Answer 1

Answer:

1)it is given that,

ⁿpr=840,

ⁿCr=35

As we know,

r!=ⁿpr/ⁿCr=840/35=24

r!=4!

r=4

2)ⁿC3/(n-1)C4=8/5

n!/(n-3)!×(n-5)!/(n-1)!=8/5

n(n-1)!/(n-3)(n-4)(n-5)!×(n-5)!/(n-1)!=8/5

n/(n-3)(n-4)=8/5

5n=8(n²-7n+12)

5n=8n²-56n+96

8n²-61n+96=0

Factorise it to get n value.....

Step-by-step explanation:

Hope it helps you frnd.......