已知<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/c5bf18cbf0f94a9987620e9e88f148ef.png?x-oss-process=image/sharpen,200"/>，<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/8edf5313d2104b7aa7087180e51b0f1c.png?x-oss-process=image/sharpen,200"/>为<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/e4795f6a92b445ce9f3a38ded41a4fca.png?x-oss-process=image/sharpen,200"/>的反函数，则<img src="http://jgxm-question.oss-cn-beijing.aliyuncs.com/psst/files/c5070811c9704a8b8487f254af5d6dd8.png?x-oss-process=image/sharpen,200"/>为（）.