若方程2x²=1的两实数根为x1 x2 则 A ：x1+x2=0且x1x2=1 B ：x1+x2=1且x1x2=0 C：x1+x2=0且x1x2=-1/2

若方程2x²=1的两实数根为x1 x2 则 A ：x1+x2=0且x1x2=1 B ：x1+x2=1且x1x2=0 C：x1+x2=0且x1x2=-1/2

x1=√2/2,x2=-√2/2
所以x1+x2=0,x1x2=-1/2
应选C