问题 选择题 若方程2x2=1的两实数根为x1、x2,则( )A.x1+x2=0且x1x2=1B.x1+x2=1且x1x2=0C.x1+x2=0且x1x2=-12D.x1+x2=0且x1x2=12 答案 解;方程2x2=1的两实数根为x1、x2,方程可化为:2x2-1=0,∴x1+x2=0且x1x2=-12,故选C.