There is a new movie Invisible guest(看不见的客人) on show. Li Hua and her parents will watch it. They can go there airy day. Please help her work out which is the lowest price for them.

Invisible guest Tuesday evening￥60                 Sunday￥80 If you have a student card, you can have a discount of 40% off If there are three persons, you can have a family price 132 for three(except weekends)

关于下列物态变化的现象，解释不正确的是（  ）

如图，二次函数y=ax²+bx+c的图象与x轴的交点的横坐标分别为﹣1，3，则下列结论正确的个数有（　　）

①ac＜0；②2a+b=0；③4a+2b+c＞0；④对于任意x均有ax²+bx≥a+b．

下列关于分式的判断，正确的是（   ）

若角α的终边与单位圆相交于点（$\frac{\sqrt{2}}{2}$，﹣$\frac{\sqrt{2}}{2}$），则sinα的值为（　　）