Question 196154
let  n =  number
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4n - ( 2*(n)(n+1) )
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4n -(2* (n^2  +n) )
4n - (2n^2 +2n )
4n -2n^2 -2n
2n -2n^2
2n ( 1-n)...ANSWER
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checking,, for  n=0,  both  original  and  answer  =0
for  n=2,  both  =  -4,,,ok