解∵f'(x)是一次函数,
∴f(x)是二次函数,可设为f(x)=ax2+bx+c(a≠0),
∴f'(x)=2ax+b.
把f(x)和f'(x)代入已知方程,得
x2(2ax+b)-(2x-1)(ax2+bx+c)=1,
整理,得(a-b)x2+(b-2c)x+c-1=0.
∴{■(a"-" b=0"," @b"-" 2c=0"," @c"-" 1=0"," )┤解得{■(a=2"," @b=2"," @c=1"." )┤
故f(x)=2x2+2x+1.
★11.设函数f(x)=ax3+bx+c(a>0)为奇函数,其图像在点(1,f(1))处的切线与直线x-6y-7=0垂直,导函数f'(x)的最小值是-12,求a,b,c的值. 学 ]
解∵f(x)是奇函数,
∴f(-x)=-f(x),
即-ax3-bx+c=-ax3-bx-c,
∴c=0.
∵f'(x)=3ax2+b的最小值为-12,且a>0,
∴b=-12.
又f(x)在点(1,f(1))处的切线与直线x-6y-7=0垂直,∴f'(1)=3a+b=-6,∴a=2.
综上可得,a=2,b=-12,c=0.