Question

If nC10 = nC12 , find 23Cn

Answer 1

u know the identity:
\(\huge ^nC_r=^nC_{n-r}\)

Answer 2

Yes

Answer 3

so here r=10
n-r=12
n-10=12
n=22
ok?

Answer 4

now
\(\huge ^{23}C_{22}=^{23}C_{23-22}=^{23}C_{1}=??\)

Answer 5

@Viks u know how to find 23C1 ?

Answer 6

Noo

Answer 7

\(\huge ^{n}C_{r}=\frac{n!}{r!(n-r)!}\)
so 23C1 will be 23!/(1!*22!)=23*22!/22!=23
ok?

Answer 8

Okay

Answer 9

If nPr =720 and nCr = 120 Find r