已知函數(shù)y=
和y=kx+1(k≠0).
(1)若這兩個(gè)函數(shù)的圖象都經(jīng)過(guò)點(diǎn)(1,a),求a和k的值;
(2)當(dāng)k取何值時(shí),這兩個(gè)函數(shù)的圖象總有公共點(diǎn).
(1)∵兩函數(shù)的圖象都經(jīng)過(guò)點(diǎn)(1,a),
∴
.
∴
.
(2)將y=
代入y=kx+1,消去y.得kx
2+x-2=0.
∵k≠O,
∴要使得兩函數(shù)的圖象總有公共點(diǎn),只要△≥0即可.
∴△=b
2-4ac=1+8k≥0,
解得k≥-
;
∴k≥-
且k≠0.