Question

104、如果抛物线y=x2-(k-1)x-k-1与x轴交于A、B,与y轴交于C,那么△ABC面积的最小值是_______

Answer 1

A(x1,0),B(x2,0)x1+x2=k-1 x1*x2=-(k+1)

判别式=（k-1)^2+4(k+1)=k^2+2k+5>0

/AB/=根号下(x1-x2)^2

=根号下[(x1+x2)^2-4x1x2]

=根号下[(k-1)^2+4(k+1)]

=根号下[k^2+2k+5]

/c/=/k+1/

S△ABC/AB/*/c//2={根号下[k^2+2k+5]}*/k+1//2=