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（　�。�

A．0個或2個

B．1個或3個

C．0個或2個或4個

D．1個或3個或5個

Answer 1

分析：根據(jù)有理數(shù)的乘法運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：解：∵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．