题目

When is cleaning walls a crime? When you’re doing it to create art, obviously. A number of street artists around the world have started expressing themselves through a practice known as reverse graffiti (涂鸦). They find dirty surfaces and paint them with images or messages using cleaning brushes or pressure hoses (高压水管). Either way, it’s the same principle: the image is made by cleaning away the dirt. Each artist has their own individual style but all artists share a common aim: to draw attention to the pollution in our cities.The UK’s Paul Curtis, better known as Moose, opera设集合为函数的定义域，集合为函数的值域，集合为不等式的解集． (1)求； (2)若，求的取值范围．