当m为何值时,方程2x²-(4m+1)x+2m²-1=0 (1)有两个不相等的实数根?
问题描述:
当m为何值时,方程2x²-(4m+1)x+2m²-1=0 (1)有两个不相等的实数根?
(2)有两个相等的实数根?
(3)没有实数根?
答
∵a=2,b=-(4m+1),c=2m²-1△=b²-4ac=[-(4m+1)]²-4×2×(2m²-1)=8m+9(1)当△>0时有两具不相等的实数根即8m+9>0 m>-9/8(2)当△=0时有两具相等的实数根 ...