设f(x)=负x平方+2(a-1)x+1在区间(-无穷大,4】上是增函数,求实数a的取值范围

问题描述:

设f(x)=负x平方+2(a-1)x+1在区间(-无穷大,4】上是增函数,求实数a的取值范围

用导数 f'(x)=-2x+2(a-1) 在(-无穷大,4】上恒大于等于0 a>=5