画对勾的三道题求解答,谢谢,帮帮忙 100
2个回答
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(4) f'(x) = 1 - 1/(1 + x) = 0, x = 0
f(0) = 0, 此为极小值
(8) f'(x) = 12x^3 - 24x^2 + 12x = 12x(x - 1)²
x = 0时取极值(极小),f(0) = 1
注:x = 1两侧f'(x)均为正,f(1)不是极值。
4.
y' = a/x + 2bx +3 = (2bx² + 3x + a)/x
2bx² + 3x + a = 2b(x - 1)(x - 2) = 2bx² - 6bx + 4b
-6b = 3, b = -1/2
a = 4b = -2
f(0) = 0, 此为极小值
(8) f'(x) = 12x^3 - 24x^2 + 12x = 12x(x - 1)²
x = 0时取极值(极小),f(0) = 1
注:x = 1两侧f'(x)均为正,f(1)不是极值。
4.
y' = a/x + 2bx +3 = (2bx² + 3x + a)/x
2bx² + 3x + a = 2b(x - 1)(x - 2) = 2bx² - 6bx + 4b
-6b = 3, b = -1/2
a = 4b = -2
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