x = 4 ∑ 1 1 x 1 0 + 4 x 9 − 1 2 x 8 − 6 4 x 7 + 3 2 x 6 + 3 8 4 x 5 + 1 2 8 x 4 − 1 0 2 4 x 3 − 7 6 8 x 2 + 1 0 2 4 x + 1 0 2 4 x 9 + 7 x 8 + x 7 − 6 9 x 6 − 6 4 x 5 + 3 2 4 x 4 + 4 6 4 x 3 − 5 6 0 x 2 − 1 2 1 2 x − 3 2 0
Find the value of the above expression to 4 decimal places.
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Nice method . But why did u leave so much space?
Did exactly the same way :)
I got 2 . 1 3 4 2 6
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Let S = x = 4 ∑ 1 1 x 1 0 + 4 x 9 − 1 2 x 8 − 6 4 x 7 + 3 2 x 6 + 3 8 4 x 5 + 1 2 8 x 4 − 1 0 2 4 x 3 − 7 6 8 x 2 + 1 0 2 4 x + 1 0 2 4 x 9 + 7 x 8 + x 7 − 6 9 x 6 − 6 4 x 5 + 3 2 4 x 4 + 4 6 4 x 3 − 5 6 0 x 2 − 1 2 1 2 x − 3 2 0
This can be written as
x = 4 ∑ 1 1 x 1 0 + 4 x 9 − 1 2 x 8 − 6 4 x 7 + 3 2 x 6 + 3 8 4 x 5 + 1 2 8 x 4 − 1 0 2 4 x 3 − 7 6 8 x 2 + 1 0 2 4 x + 1 0 2 4 x 9 + 6 x 8 − 6 4 x 6 − 9 6 x 5 + 1 9 2 x 4 + 5 1 2 x 3 − 7 6 8 x − 5 1 2 + ( x 8 − 1 6 x 6 + 9 6 x 4 − 2 5 6 x 2 + 2 5 6 ) + ( x 7 + 1 0 x 6 + 3 6 x 5 + 4 0 x 4 − 8 0 x 3 − 2 8 8 x 2 − 3 8 0 x − 1 2 8 ) + ( x 6 − 4 x 5 − 4 x 4 + 3 2 x 3 − 6 4 x + 6 4 − 1 6 x 2 )
After factorizing:
S = x = 4 ∑ 1 1 ( x + 2 ) 4 ( x − 2 ) 3 ( x + 2 ) 2 ( x − 2 ) ( x + 2 ) 4 ( x − 2 ) 3 ( x + 2 ) 2 + ( ( x + 2 ) 4 ( x − 2 ) 3 ( x − 2 ) ) + ( x + 2 ) 4 ( x + 2 ) 2 ( x − 2 ) + ( ( x − 2 ) 3 ( x + 2 ) 2 ( x − 2 ) )
This gives us .
S = x = 4 ∑ 1 1 ( x + 2 ) 4 1 + ( x − 2 ) 3 1 + ( x + 2 ) 2 1 + ( x − 2 ) 1
On simplifying, we get
6 4 1 + 2 3 1 + 6 2 1 + 2 1 ⋯ ⋯ ⋯ ⋯
Therefore S is telescopic and on simplification gives the answer 2 . 1 3 4 6