设函数f(x)=x^3-3ax+b(a不等于0) (1)若曲线y=f(x)在点(2,f(2))处与直线y=3x+8相切,求a,b的值?(2)...设函数f(x)=x^3-3ax+b(a不等于0) (1)若曲线y=f(x)在点(2,f(2))处与直线y=3x+8相切,求a,b的值?(2)求函数f(x)的单调区
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![设函数f(x)=x^3-3ax+b(a不等于0) (1)若曲线y=f(x)在点(2,f(2))处与直线y=3x+8相切,求a,b的值?(2)...设函数f(x)=x^3-3ax+b(a不等于0) (1)若曲线y=f(x)在点(2,f(2))处与直线y=3x+8相切,求a,b的值?(2)求函数f(x)的单调区](/uploads/image/z/4113084-12-4.jpg?t=%E8%AE%BE%E5%87%BD%E6%95%B0f%28x%29%3Dx%5E3-3ax%2Bb%28a%E4%B8%8D%E7%AD%89%E4%BA%8E0%29+%281%29%E8%8B%A5%E6%9B%B2%E7%BA%BFy%3Df%28x%29%E5%9C%A8%E7%82%B9%282%2Cf%282%29%29%E5%A4%84%E4%B8%8E%E7%9B%B4%E7%BA%BFy%3D3x%2B8%E7%9B%B8%E5%88%87%2C%E6%B1%82a%2Cb%E7%9A%84%E5%80%BC%3F%282%29...%E8%AE%BE%E5%87%BD%E6%95%B0f%28x%29%3Dx%5E3-3ax%2Bb%28a%E4%B8%8D%E7%AD%89%E4%BA%8E0%29+%281%29%E8%8B%A5%E6%9B%B2%E7%BA%BFy%3Df%28x%29%E5%9C%A8%E7%82%B9%282%2Cf%282%29%29%E5%A4%84%E4%B8%8E%E7%9B%B4%E7%BA%BFy%3D3x%2B8%E7%9B%B8%E5%88%87%2C%E6%B1%82a%2Cb%E7%9A%84%E5%80%BC%3F%282%29%E6%B1%82%E5%87%BD%E6%95%B0f%28x%29%E7%9A%84%E5%8D%95%E8%B0%83%E5%8C%BA)
设函数f(x)=x^3-3ax+b(a不等于0) (1)若曲线y=f(x)在点(2,f(2))处与直线y=3x+8相切,求a,b的值?(2)...设函数f(x)=x^3-3ax+b(a不等于0) (1)若曲线y=f(x)在点(2,f(2))处与直线y=3x+8相切,求a,b的值?(2)求函数f(x)的单调区
设函数f(x)=x^3-3ax+b(a不等于0) (1)若曲线y=f(x)在点(2,f(2))处与直线y=3x+8相切,求a,b的值?(2)...
设函数f(x)=x^3-3ax+b(a不等于0) (1)若曲线y=f(x)在点(2,f(2))处与直线y=3x+8相切,求a,b的值?(2)求函数f(x)的单调区间与极值点
设函数f(x)=x^3-3ax+b(a不等于0) (1)若曲线y=f(x)在点(2,f(2))处与直线y=3x+8相切,求a,b的值?(2)...设函数f(x)=x^3-3ax+b(a不等于0) (1)若曲线y=f(x)在点(2,f(2))处与直线y=3x+8相切,求a,b的值?(2)求函数f(x)的单调区
1、f'(x)=3x²-3a.f'(2)=12-3a=3.又(2,f(2))在y=3x+8上,得f(2)=14=8-6a+b.解方程组:8-6a+b=14及12-3a=3,得:a=3,b=24.2、f'(x)=3(x-√3)(x+√3),(-∞,-√3)增(-√3,√3)减(√3,+∞)增
1)
f'(x)=3x^2-3a
f'(2)=12-3a=3,a=3
f(2)=8-18+b=14,b=24
2)
f'(x)=3(x+根号3)(x-根号3)
(-∞,-根号3)(根号3,+∞)增
(-根号3,根号3)减
极大=f(-根号3)=6根号3+24
极小=f(根号3)=-6根号3+24
f`(x)=3x^2-3a
f`(2)=12-3a=3
a=3
f(2)=3*2+8=14=8-18+b=14
b=24
f(x)=x^3-9x+24
f`(x)=3x^2-9=0
x=±√3
增区间(-∝,-√3) U(√3,+∝)
减区间(-√3,√3)
极大值f(-√3)=6√3+24
极小值f(√3)=-6√3+24
(1)因为y=f(x)在点(2,f(2))与直线相切,因此斜率相同 f'(x)=3x^2-3a,所以f'(2)=3(3为直线的斜率)=3*2^2-3a, 解得a=3,在x=2时,f(2)等于直线在x取2时的值,即f(2)=8-6a+b=3*2+8,得b=24 ...
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(1)因为y=f(x)在点(2,f(2))与直线相切,因此斜率相同 f'(x)=3x^2-3a,所以f'(2)=3(3为直线的斜率)=3*2^2-3a, 解得a=3,在x=2时,f(2)等于直线在x取2时的值,即f(2)=8-6a+b=3*2+8,得b=24 从而a=3,b=24得解 (2)f'(x)=3x^2-9,f'(x)>0单调递增,得x取(根号3,正无穷)和(负无穷,负根号3),f'(x)< 0 单调递减 得取(负根3,正根3), 当f'(x)=0时取极值,得x=正负3
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