-1-(-2)-(-3)-(-4)-.-(-19)-(-20)怎样解答

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-1-(-2)-(-3)-(-4)-.-(-19)-(-20)怎样解答
-1-(-2)-(-3)-(-4)-.-(-19)-(-20)怎样解答

-1-(-2)-(-3)-(-4)-.-(-19)-(-20)怎样解答
(1+2+...+20)-2
=21*10-2
=208

1 2 3 4 1 2 3 4 1 2 3 4 1,2,3,4, 1 2 3 4 1 2 3 4 1,2,3,4, 1,2,3,4, 1,2,3,4, 1,2,3,4, 1 2 3 4 1,2,3,4, 1,2,3,4, 1,2,3,4, 1、2、3、4 1+2+3×4 1,2,3,4 1+2+3+4+.