已知a=1/20x+20,b=1/20x+19,c=1/20x+21,求代数式a^2+b^2+c^2-ab-bc-ac的值

已知a=1/20x+20,b=1/20x+19,c=1/20x+21,求代数式a^2+b^2+c^2-ab-bc-ac的值
已知a=1/20x+20,b=1/20x+19,c=1/20x+21,求代数式a^2+b^2+c^2-ab-bc-ac的值

已知a=1/20x+20,b=1/20x+19,c=1/20x+21,求代数式a^2+b^2+c^2-ab-bc-ac的值
a^2+b^2+c^2-ab-bc-ac=【(a-b)+(a-c)+(b-c)】/2=3
这就OK了!

Lucid Dreaming is a powerful skill for making changes in yourself and your life. Also known as conscious dreaming, a lucid dream is one in which you are aware you are dreaming. Your body is asleep but...

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Lucid Dreaming is a powerful skill for making changes in yourself and your life. Also known as conscious dreaming, a lucid dream is one in which you are aware you are dreaming. Your body is asleep but your mind is awake and aware. When you are in the lucid dream state, you can actively participate in and manipulate the dream. The benefits of lucid dreaming are many. As you develop the ability to lucid dream the quality of your sleep will be better. It will be deeper and more restful, and as a result, you will require less sleep overall. One reason is that material that has gone unprocessed from your day or from the past gets worked out in the dreamtime. In the lucid dream state you will gain access to your subconscious mind and be able to work with the material presented to you in a conscious way. You can resolve personal issues and generate solutions to life situations rapidly and with deep effects because you are already working at the level of the subconscious mind where real change occurs.In addition, you will find that lucid dreaming enhances your intuitive and psychic abilities. The conscious mind uses language as its main means for communicating. The subconscious mind uses the language of symbolic imagery. By practicing being aware in the dream state you develop the ability to be able to read these symbolic messages. Over time, the experience of flashes of insight increases in the waking state along with a greater understanding of these insights because the practice has created a clearer line of communication between your conscious and subconscious mind. As a result, you will function more optimally with intuitive flashes and insights becoming much more a part of your daily life.To begin lucid dreaming,Brand Hair Straightener, the first thing is to start remembering your dreams. This is done by keeping a dream journal. Buy a notebook and a pen to keep a record of your dreams and place it by your bed at night. Before you go to sleep, take a minute, and repeat a clear and strong statement of intention to yourself several times, ?I will remember at least two dreams by the time I wake up.? This statement of intention is the first communication with your subconscious mind to set up the agreement that you are ready to begin remembering your dreams. As you drift off to sleep, trust that when you awaken you will remember your dreams in the morning.When you wake up, stay in bed for a few minutes in the dreamy drowsy state known as the hypnogogic state,Comb, and with your eyes still closed, try and recall anything you can from the night before. Anything. Whatever it is, even if it is a vague recollection, write it down. If you don?t remember anything that?s fine. Simply, continue the process and you will find that each morning you will remember more. If you remember something during the course of the day make a notation and include it in your dream journal when you get home. When you record your dreams, refrain from analyzing them as you write them down. Just write down whatever comes to you and as much as you can remember. By the end of a few weeks you will be recalling a great deal of dream material.The second step is done during waking hours. Go through your dream journal and find some event or imagery that repeats itself. Make sure it?s also something that happens to you in your waking life. Pick one of the repeated elements of your dream and whenever you experience that same thing in your waking life, stop and ask yourself, ?Am I dreaming??For example, if you see your hands in your dreams then throughout the course of your day look at your hands and ask yourself the question, ?Am I dreaming?? As another example, if you find that you walk through doorways in your dreams then whenever you walk through a doorway in your waking life touch the door jamb and ask,Hair Straighteners Ceramic, ?Am I dreaming?? This sets up an anchor for remembering. At some point, you will have a dream and, as you see your hands or walk through a doorway or whatever it is you choose to remember, you will reflexively ask the question, ?Am I dreaming?? This time the answer will be ?yes?,Hair Straightener, and,Flat Iron Hair Straighteners, chances are, that you will find yourself suddenly awake inside the dream!When you are awake inside the dream you can begin to watch the dream unfold. As you remain in the lucid state you can begin to change and manipulate the dream in different ways. In the beginning, you will be awake and watching the dream like a movie, but over time you will find that you possess greater and greater ability to control the dream and the way it unfolds. Eventually, you will be able to choose what you want to dream and can even begin dreaming about events of the day or of your past where you can change the outcome in ways that serve your highest fulfillment. Changing these events from your day or your past to outcomes that you desire will have a positive effect on your psyche, sense of well-being and self-mastery. You will be reprogramming your subconscious mind to accept the best possible solution or response to an issue or situation and it will make the appropriate changes in your subconscious. You will find that it has a dramatic effect on your waking life, as well. As you become very good at lucid dreaming you can even take future events into the dreamtime and work with them so the outcomes manifest in the way you desire!Have fun, practice, and we?ll see you in the dreamtime!

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a^2+b^2+c^2-ab-bc-ac
=2（a^2+b^2+c^2-ab-bc-ac）÷2
=（2a^2+2b^2+2c^2-2ab-2bc-2ac)÷2
=[(a^2-2ab+b^2)+(a^2-2ac+b^2)+(b^2-2bc+c^2)]÷2
=[(a-b)^2+（a-c)^2+(b-c)^2]÷2
代入得
原式=-1