4. lim
= lim
lim
= lim
lim
b = 1.
左导数 lim
= lim
右导数 lim
= lim
= lim
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。