题目

San Francisco has many museums. You can visit one and learn something new. We have art, science, history and other special museums. Some museums are open every day. Some are only open on certain days. Many museums are expensive, and others are free. But some of the expensive ones have free days . May museums have websites. The websites usually have information about the things you can see in the museums. On a museum’s website you can get information about ticket prices and free days. You can also know where the museum is and when it is open. Sometimes the information is on the first page, a已知f（x）=alnx-bx2图象上一点P（2，f（2））处的切线方程为y=-3x+2ln2+2．（1）求f（x）的单调增区间；（2）令g（x）=f（x）-kx（k∈R），如果g（x）图象与x轴交于A（x1，0），B（x2，0）（x1＜x2）两点，AB的中点为G（x0，0），问g（x）在x=x0处是否取得极值．