题目

已知，则的最小值为（ ）A. 2 B. 1 C. 4 D. 3 答案：【答案】C【解析】将的表达式构造成可以利用基本不等式求解最小值的形式.因为，所以，取等号时即，故选：C.Exerpeutic 15-0125 InStride Folding Cycleby Exerpeutic3.8 out of 5 stars 625 customer reviewsList Price: $70.00Price: $29.22 & FREE DELIVERY on orders over $35. Portable folding exercise bike that sits on a tabletop or on the floor Battery-operated electronic monitor times your workout Convenient tension control offers several resistance levels Sturdy nonslip rubber feet; sturdy foot straps for stabilityDeskCycle Desk Exercise Bike Pedal Exerciser (White)by DeskCycle4.7 out of 5 stars 786 customer reviewsList Price: $199.00Price: $159.00 & FREE DELIVERY. Lowest pedal height available; Only 10 Inches; Can work with desks as low as 27 Inches More than twice the resistance range of the other pedal exercisers; 8 calibrated resistance settings; from very easy to more than you need Magnetic resistance provides smooth, quiet pedal motion; let you focus on your work and your co-workers focus on theirs 5 function display shows speed, time, distance calories and scanStamina 15-0120 InStride Cycle XL by Stamina3.6 out of 5 stars 747 customer reviewsList Price: $60.00Price: $31.63 & FREE DELIVERY on orders over $35. Seatless-exercise cycle with electric progress monitor Sturdy rubber straps hold feet or hands for full-body workout Adjustable tension knob lets you vary workout intensity Improves cardiovascular health and muscle strengthMagneTrainer-ER Mini Exercise Bike Arm and Leg Exerciserby MagneTrainer4.5 out of 5 stars 477 customer reviewsList Price: $189.00Price: $159.00 & FREE DELIVERY. Compact, lightweight commercial grade arm and leg exerciser Patented magnetic resistance; More than twice the resistance range of the other magnetic pedal exercisers Adjustable Velcro straps on pedals to accommodate all foot sizes; pedals work with both feet and hands Electronic monitor displays Speed, Distance, Time and Calories. Runs on single AA Battery (included)1.Which product offers you the biggest discount?A. Stamina 15-0120 InStride Cycle XLB. Exerpeutic 15-0125 InStride Folding CycleC. DeskCycle Desk Exercise Bike Pedal ExerciserD. MagneTrainer-ER Mini Exercise Bike Arm and Leg Exerciser2.If you want to exercise without disturbing others at work, you can choose the item from ______.A. Stamina B. ExerpeuticC. MagneTrainer D. DeskCycle58. According to the passage, we can infer that ______.A. you don’t have to pay for the delivery of the items advertisedB. the producers may be trying to reduce the range of resistanceC. the limit of choice in color may affect the popularity of the productD. the monitoring system is something these products have in common