A class collects ＄50 to buy flowers for a classmate who is in the hospital. Roses cost ＄3 each， and carnations cost ＄2 each. No other flowers are to be used. How many different bouquets could be purchased for exactly ＄50？_______
若a>0，a
1，F（x）为偶函数，则G（x）＝F（x）·log
（x＋
）是_______函数（填“奇”或“偶”），它的图像关于______对称。
已知f（x）＝x
＋（a－1）x＋a在区间
上是增函数，则a的取值范围是______
For real numbers ａ and b， define a＄b＝（a－b）
. What is （x－y）＄（y－x）？______
的离心率为_________．