(2002•宁德)在公式
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中,已知t、d,则D=
.
考点分析:
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,则
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=
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(2002•昆明)下列结论正确的是( )
①方程
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=-2没有实数根;
②解方程(
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)
2-2(
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)=0时,若设y=
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,则原方程变形为y
2-2y-3=0;
③存在这样的两个实数a、b,使得
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;
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B.①②④
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=0
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