大一高等数学 函数的连续性!求解答

大一高等数学 函数的连续性!求解答一共三道题 最好能写出步骤
2024-11-24 04:14:19
推荐回答(1个)
回答1:

4. limf(x) = lim(1-cosax)/x
= lim(ax)^2/(2x) = 0 = f(0),
limf(x) = lim[√(b+x^2)-1]/x
= lim[√b√(1+x^2/b)-1]/x
lim[√b+x^2/(2√b)-1]/x = 0
b = 1.
左导数 lim[f(x)-f(0)]/(x-0)
= lim(1-cosax)/x^2 = a^2/2
右导数 lim[f(x)-f(0)]/(x-0)
= lim[√(1+x^2)-1]/x^2
= lim(x^2/2)/x^2 = 1/2,
a^2/2 = 1/2, a = ±1.
1. (1) f(x) = (x-3)/[x((x-3)(x+2)]
间断点 x = -2, 0, 3,
x = -2, 0 为无穷间断点, x = 3 为可去间断点。
(2) f(x) = (x-1)(x+1)/[((x-1)(x-2)]
间断点 x = 1, 2,
x = 2 为无穷间断点, x = 1 为可去间断点。