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標題:

跪求微積分高手幫我解題

發問:

f(x)=x4-4x3+10x-9 求： 1.increasing intervals 2.decreasing intervals 3.intervals of concave upward 4.intervals of concave downward 5.max or min 6.graph

最佳解答:

y(x) = x^4 - 4x^3 + 10x - 9 = 0=> x = 3.35, -1.653 by computer y'(x) = 2(2x^3 - 6x^2 + 5) = 0x = 2.64, 1.168, -0.810 by computer y"(x) = 12x(x - 2)y"(2.64) > 0 => miny"(1.168) maxy"(-0.810) > 0 => minShown as the Figure. 1.increasing intervalsx = 2.64 3.intervals of concave upwardx = 1.168 4.intervals of concave downwardx = -0.891 ~ 2.64 5.rel max = y(1.168) = -1.83rel min = y(-0.891) = -14.45rel min = y(2.64) = -7.62 6. 圖片參考：https://s.yimg.com/rk/AD06198854/o/638104097.png

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