Find the value of
1 + a + 2 b + 3 c + 2 a b + 3 a c + 6 b c + 6 a b c ,
when a = 8 8 8 , b = 6 6 6 , and c = 4 4 4
Hint: Try to simplify
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Notice that 1 4 4 d 3 + 8 4 d 2 + 1 6 d + 1 = ( 4 d + 1 ) ( 6 d + 1 ) 2 . This extra factorisation reduces the problem to multiplying 1 3 -digit number, 1 4 -digit number, and another 4 digit number.
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Yeah ! Thanks. Good idea. I will have it changed soon.
1 + a + 2 b + 3 c + 2 a b + 3 a c + 6 b c + 6 a b c
= ( a + 1 ) ( 2 b + 1 ) ( 3 c + 1 ) = ( 8 8 8 + 1 ) ( 2 ∗ 6 6 6 + 1 ) ( 3 ∗ 4 4 4 + 1 )
= 8 8 9 ∗ 1 3 3 3 ∗ 1 3 3 3 = 1 5 7 9 6 5 4 3 2 1
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1 + a + 2 b + 3 c + 2 a b + 3 a c + 6 b c + 6 a b c
Well lets make a new letter named d which is equal to 2 2 2 , So it means that:
a = 4 d
b = 3 d
c = 2 d
Now simplifying the above expression using these codes will make it:
1 + 4 d + 2 ( 3 d ) + 3 ( 2 d ) + 2 ( 4 d ) ( 3 d ) + 3 ( 4 d ) ( 2 d ) + 6 ( 4 d ) ( 3 d ) ( 2 d )
1 + 4 d + 6 d + 6 d + 2 4 d 2 + 2 4 d 2 + 3 6 d 2 + 1 4 4 d 3
1 + 1 6 d + 8 4 d 2 + 1 4 4 d 3
Now we can simply substitute the value of d into this equation:
1 + 1 6 d + 8 4 d 2 + 1 4 4 d 3
which can be factorized into:
( 4 d + 1 ) ( 6 d + 1 ) 2
Now we can substitute 2 2 2 into the expression:
( 4 ( 2 2 2 ) + 1 ) ( 6 ( 2 2 2 ) + 1 ) 2
Which is equal to
= 1 5 7 9 6 5 4 3 2 1