设二次方程x²+px+q=0的两个实数根恰为p,q,则pq的值是() A.0 B.-2 C.0或-2 D.
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设二次方程x²+px+q=0的两个实数根恰为p,q,则pq的值是() A.0 B.-2 C.0或-2 D.
设二次方程x²+px+q=0的两个实数根恰为p,q,则pq的值是() A.0 B.-2 C.0或-2 D.
设二次方程x²+px+q=0的两个实数根恰为p,q,则pq的值是() A.0 B.-2 C.0或-2 D.
由韦达定理得
P+Q=-P①
PQ=Q②
解得
{P=1
{Q=-2
PQ=-2
选B