Question

n The number of values of n e N for which n+2C2, :+3 C1 = 4:2 is
​

Answer 1

Answer:

-1

Step-by-step explanation:

Adding and subtracting

n

C

0

we get

[

n

C

0

+

n

C

1

+

n+1

C

2

+

n+2

C

3

...+

n+m−1

C

m

]−

n

C

0

Applying the formula

n

C

r

+

n

C

r+1

=

n+1

C

r+1

we get

[

n+1

C

1

+

n+1

C

2

+

n+2

C

3

...+

n+m−1

C

m

]−

n

C

0

=[

n+2

C

2

....+

n+m−1

C

m

]−1

:

:

:

=

n+m−1

C

m−1

+

n+m−1

C

m

−1

=

n+m

C

m

−1