问题标题：
【一道GMAT数学题,求高人指教.Forafinitesequenceofnonzeronumbers,thenumberofvariationsinsignisdefinedasthenumberofpairsofconsecutivetermsofthesequenceforwhichtheproductofthetwoconsecutivetermsisnegative.Whati】
问题描述：
一道GMAT数学题,求高人指教.
Forafinitesequenceofnonzeronumbers,thenumberofvariationsinsignisdefinedasthenumberofpairsofconsecutivetermsofthesequenceforwhichtheproductofthetwoconsecutivetermsisnegative.Whatisthenumberofvariationsinsignforthesequence1,-3,2,5,-4,-6
(A)One
(B)Two
(C)Three
(D)Four
(E)Five
康晓东回答：
C
thenumberofvariationsinsign的定义是那些相邻(consecutive)两项乘积为负的数的对数(pairs)
观察知道1,-3;-3,2;5,-4;这三组数成立
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