cc啊灌水
幼苗
共回答了22个问题采纳率:95.5% 举报
f(x)=-x^3+ax^2+bx+c的导函数:f‘(x)=-3x²+2ax+b点p(1,-2)处的切线方程为y=-3x+1.所以f‘(1)=-3 => 2a+b=0 ①点p(1,-2)满足f(x)解析式即f(1)=-2 => -1+a+b+c=-2 => a+b+c=-1 ②(1)若函数f(x)在x=-2时有极值,则f‘(-2)=0 => -12-4a+b=0 ③①②③联立解得:a=-2,b=4,c=-3f(x)表达式为f(x)=-x^3-2x²+4x-3
1年前
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