Question

y=ax^3+bx^2+cx+d以y(-2)=44为极值,函数图形以(1,10)为拐点,求a,b,c,d,的值

Answer 1

一阶导数3ax^2+2bx+c=0,x=-2代入,12a-4b+c=0

二阶导数6ax+2b=0,x=1代入,6a+2b=0

原式x=-2时,y=44,-8a+4b-2c+d=44

x=1时,y=10,a+b+c+d=10