Q. 235.0( 1 Vote )
Mark the correct alternative in the following:
The value of 
is
A. 
B. 
C. 
`
D. 
Answer :
( 7C0 + 7C1 ) + ( 7C1 + 7C2 ) + ( 7C2 + 7C3 ) + ( 7C3 + 7C4 ) + ( 7C4 + 7C5 ) + ( 7C5 + 7C6 ) + ( 7C6 + 7C7 )
= 1 + 2
7C1 + 2
7C2 + 2
7C3 + 2
7C4 + 2
7C5 + 2
7C6 + 1
= 1 + 2
7C1 + 2
7C2 + 2
7C3 + 2
7C3 + 2
7C2 + 2
7C6 + 1 ⇒ (7C3 = 7C4 and 7C2 = 7C5)
= 2 + 22 (7C1 + 7C2 + 7C3)
= 2 + 22 (7 + 
6 + 
5)
= 2 + 252
= 254
= 28 – 2
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