$解：?(2)?把?x=k?代入?y=-x-1，?得?y=-k-1，?$
$則?A_1?的坐標(biāo)是?(k，??-k-1)；?$
$把?x=k?代入?y=\frac {1}{x}?得：?y=\frac {1}{k}，?$
$則?B_1?的坐標(biāo)是?(k，??\frac {1}{k})；?$
$把?y=\frac {1}{k}?代入?y=-x-1?得：?\frac {1}{k}=-x-1?$
$解得：?x=-\frac {k+1}{k}，?即?A_2?的坐標(biāo)是?(-\frac {k+1}{k}，??\frac {1}{k})；?$
$把?x=-\frac {k+1}{k}?代入?y=\frac {1}{x}?得：?y=-\frac {k}{k+1}?$
$則?B_2?的坐標(biāo)是?(-\frac {k+1}{k}，??-\frac {k}{k+1})?$
$把?y=-\frac {k}{k+1}?代入?y=-x-1，?得：?x=-\frac {1}{k+1}?$
$即?A_3?的坐標(biāo)是?(-\frac {1}{k+1}，??-\frac {k}{k+1})；?$
$把?x=-\frac {1}{k+1}?代入?y=\frac {1}{x}?得：?y=-k-1?$
$則?B_3?的坐標(biāo)是?(-\frac {1}{k+1}，??-k-1)?$
$把?y=k+1?代入?y=-x-1?得?x=k，?則?A_4?的坐標(biāo)是?(k，??-k-1)，?即?A_1?$
$則點(diǎn)?A_{n}?的橫坐標(biāo)分別是：?k，??-\frac {k+1}{k}，??-\frac {1}{k+1}，?···三個(gè)循環(huán)一次$
