Question

if npr-1/a = npr/b = npr+1/c then the value of b2/a(b+c) =​

Answer 1

Answer:

Step-by-step explanation:

ⁿPr=ⁿPr+1

or, n!/(n-r)!=n!/(n-r-1)!

or, n!/(n-r)(n-r-1)!=n!/(n-r-1)!

or, 1/(n-r)=1

or, n-r=1 ------------------(1)

Again,

ⁿCr=ⁿCr-1

or, n!/r!(n-r)!=n!/(r-1)!(n-r+1)!

or, 1/r(r-1)!(n-r)!=1/(r-1)!(n-r+1)(n-r)!

or, 1/r=1/(n-r+1)

or, r=n-r+1

or, n-2r=-1 --------------------(2)

Subtracting (2) from (1) we get,

n-n-r+2r=1+1

or, r=2

Putting in (1),

n-2=1

or, n=3

∴, n=3, r=2