Question

A={x/2a≤x≤a+3}.B={x/x＜-1或x＞5}.求：①若A∩B≠空集，求a的取值范围.②若A∪B＝R（R为实数集）

A={x/2a≤x≤a+3}.B={x/x＜-1或x＞5}.求：①若A∩B≠空集，求a的取值范围.②若A∪B＝R（R为实数集），求a的取值范围.最好要有解题过程

Answer 1

1.画数轴，只要A有一部分在B上就是A∩B≠空集
∴A≠空集
∴2a≤a+3 又∵2a＝a+3即a=3，A=3，不符合题意（舍去）
∴2a＜a+3即a＜3
①当2a＜-1时A∩B≠空集即a＜-1
②当2a≥-1时要使得A∩B≠空集应该使a+3＞5即a＞2
∴2＜a＜3
综上所述a＜-1或2＜a＜3
2.∵A∪B＝R且a＜3
∴2a＜-1且a+3＞5无解
∴不存在a使得A∪B＝R

Answer 2

Basketball is a strenuous exercise, in order to cope with intense exercise, for a pair of air jordan for sale basketball shoes is concerned, we need to have good durability, support, stability, comfort and good vibration. Basketball constant starting, emergency stop, take off and quickly move around other action to make your selection of basketball shoes in the shoes of the properties must be on the absolute top. Also, play your own style is a very important factor, according to the choice they need different types of basketball shoes. Basketball shoes for maintenance and placed the environment descriptionBasketball shoes that Air jordan force fusion, will also SNEAKER shoes lovers into the term,Air Jordan 8, making SNEAKER more broad definition.Basketball is a demanding sport, in order to meet their requirements, speaking for a pair of basketball shoes, you need to have good durability, support, stability, flexibility and good music and damping effect. Basketball constant starting, emergency stop, take off and quickly move around other action to make your selection of basketball shoes in the shoes of the properties must be on the absolute top. Also, Maintenance of basketball shoes has two purposes: First performance of maintenance, the second is the appearance and maintenance. Performance of the maintenance method of the correct key is saved on the shoes, but the appearance and maintenance is mainly reflected in the scientific cleaning air jordan for sale shoes, but sometimes the two are one. in preservation methods,Air Jordan, types of raw materials as basketball shoes, more production, such as a pair of basketball shoes on the use of materials is likely to include leather, cloth, nylon, play your own style is a very nike hat important factor,Kids Jordan Shoes, according to the choice they need different types of TreadTang basketball shoes.non-dragon, no trace of rubber, etc., resulting more complex production processes, glue stick together more than a place also. It is these materials to ensure performance with a pair of shoes, while maintaining performance is the proper handling of a pair of shoes,Authentic Jordan Shoes, so that the above-mentioned materials Buzhi Yu aging. So the correct way to write the preservation of the following points should be noted.display environment: First,AJ 23 Shoes, it should be put shoes on a relatively dry and ventilated place, avoid direct sunlight, because the humid environment may cause corruption body shoes, shoes, sun exposure will change color as part of material deterioration. But where the shoe has not too dry, because the result in cracking of leather. Because the humid cool nike environment may cause corruption body shoes, shoes, sun exposure will change color as part of material deterioration. Second, save the shoes when the shoes should be stuffed in a soft ball of paper, the main purpose in doing so is ball of paper can absorb water shoes to keep the internal residual dry inside, but also conducive to maintaining a fixed shape of shoes, not As for the after use of the "Beat." Third, special needs raised Di yes type for collection preservation, better buy Yi Xie shrink film, like shoe stores inside like putting a pair of shoes Wanquan wrap, in order to obtain the shoes of the large extent of and Kongqigeli, Fang Zhi longer Yiduanshijian constant air oxidation of the shoes. For example, the visible air cushion, such as nike max air or on behalf of Jordan, 11, 16 on behalf of the foreign end of a few years time, will gradually turn yellow, with the shrink film to maintain the original color is a better choice. air jordan for sale shoe different from the air jordan for sale, so it's maintenance and display environment, paying particular attention to, so as to ensure its quality is better and wear longer