已知抛物线y=x2+bx+c与y轴的正半轴交于点A,与x轴的正半轴交于B、C两点,且BC=2,S△ABC=3,则bc= _ .
已知抛物线y=x2+bx+c与y轴的正半轴交于点A,与x轴的正半轴交于B、C两点,且BC=2,S△ABC=3,则bc= ___ .
数学人气:360 ℃时间:2019-10-27 17:48:09
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∵抛物线y=x2+bx+c与y轴交于点A,令x=0得,A(0,c),∵该抛物线的开口向上,且与x轴的正半轴交于B、C两点,∴抛物线与y轴的交点在y轴的正半轴,∴c>0,设方程x2+bx+c=0的两个根为x1,x2,∴x1+x2=-b,x1x2=c,∵B...
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