已知函数g(x)=ax3+bx2+cx(a∈R且a≠0),g(-1)=0,且g(x)的导函数f(x)满足以f(0)f(1)≤0.
已知函数g(x)=ax3+bx2+cx(a∈R且a≠0),g(-1)=0,且g(x)的导函数f(x)满足以f(0)f(1)≤0.
日期:2016-04-24 10:15:45 人气:1
由题意得:f(x)=3ax2+2bx+c,∵g(-1)=0,∴c=-a+b,∵方程3ax2+2bx+c=0有两个实根,∴△=4b2-12ac≥0,即4b2-12a(b-a)≥0,b2-3ab+3a2≥0,它恒成立,∵f(0)?f(1)≤0,f(0)=c=-a+b,f(1)=3a+2b+c=2a+3b,∴(-a+b)(2a+3b)≤0,即3(ba-1)(ba+23)≤0,所以-23≤ba≤1,故选C.