Question

若五個有理數(shù)的積是負(fù)數(shù)，則這五個有理數(shù)中正因數(shù)的個數(shù)是

1. A.
   0個或2個
2. B.
   1個或3個
3. C.
   0個或2個或4個
4. D.
   1個或3個或5個

Answer 1

C
分析：根據(jù)有理數(shù)的乘法運(yùn)算符號法則判斷出負(fù)因數(shù)的個數(shù)，然后求出正因數(shù)的個數(shù)即可．
解答：∵五個有理數(shù)的積是負(fù)數(shù)，
∴負(fù)因數(shù)的個數(shù)是1或3或5個，
∴正因數(shù)的個數(shù)為4或2或0個．
故選C．
點評：本題考查了有理數(shù)的乘法，熟記幾個不等于零的數(shù)相乘，積的符號由負(fù)因數(shù)的個數(shù)決定：當(dāng)負(fù)因數(shù)有奇數(shù)個數(shù)，積為負(fù)；當(dāng)負(fù)因數(shù)的個數(shù)為偶數(shù)個時，積為正．