抛物线y=4x²-4(k+1)x+4k-1与y轴相交于(x1,0) (x2,0 ) 两点 且0<x1<1<x2<2 则k的取值范围是
问题描述:
抛物线y=4x²-4(k+1)x+4k-1与y轴相交于(x1,0) (x2,0 ) 两点 且0<x1<1<x2<2 则k的取值范围是
答
f(x)=4x²-4(k+1)x+4k-1开口向上
则画图可知
f(0)=4k-1>0,k>1/4
f(1)=4-4k-4+4k-10,kk