'( ),( ) ( ),f x g xf x g x?????即200320 0 03 9 6 ,9 3 ,xxx x x a?????? ????解得0327xa??????或015xa??????,所以27a??或5a?.-(Ⅱ)若存在实数b使不等式( ) ( )f x g x?的解集为( , )b??,即3239x x x a? ??的解集为( , )b??.文科参考答案第6页,共6页令32( ) 3 9h x x x x? ??,则()y h x?的图象在直线ya?下方的部分对应点的横坐标x?( , )b??.2'( ) 3 6 9h x x x? ??,由'( ) 0hx?解得123, 1xx? ??,'( ), ( )f x f x的情况如下:x( , 1)???1?( 1,3)?3(3, )??()hx+0?0+'( )hx极大值极小值因为2 2 4 2 2( 5) ( 5)( 7 1) 5 2 5| |h a a a a a a a? ????????,即2( 5)h a a??;2 2 4 2 2( 2) ( 2)( 7 1) ( 2) 2 2 | |h a a a a a a a? ????????????,即2( 2)h a a? ??,(或者:因为当x???时,()hx???,当x???时,()hx???)又因为( ) = ( 1) 5h x h??极大值,( ) = (3) 27h x h??极小值,所以当5a?或27a?≤满足条件.(两个区域各1分)(Ⅲ)11a??.
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