若关于x的方程x2-k|x|+4=0有四个不同的解，则k的取值范围是______
题型：填空题
问题：
若关于x的方程x2-k|x|+4=0有四个不同的解，则k的取值范围是______．
题型：填空题
Directions: Read the following passage. Answer the questions according to the information given in the passage and the required words limit. Write your answers on your answer sheet.
Several years ago, Masaru Ibuka, the chairman of Sony, was at a company planning a meeting. Suddenly he had a brilliant idea. He stopped the meeting and asked everyone present what would happen if Sony removed the recording function and speaker and sold headphones with a tape player instead. Almost everyone thought he was crazy. Still, Ibuka kept thinking about his idea and worked at refining it. The result, of course, turned out to be the wildly successful Sony Walkman.
Good ideas often start
with a really silly question. Bill Bowerman was making breakfast one day. As he stood there making waffles(蛋奶烙饼)for his son, he wondered what would happen if he poured rubber into his waffle iron(蛋奶烙饼烤模).So, he tried and the result looked something like the bottom of most sports shoes we see today. Still,when he took this idea to several existing shoe companies he was literally(确实地)laughed at. In fact, every single company turned him down. Though rather disappointed. Bowerman was determined and went on to form his own company, making NIKE athletic shoes.
Sometimes good ideas grow out of frustration. When Fred Smith was a student at Yale University, he had some paperwork that he needed to have delivered across the country the next day. Smith was amazed to find out that overnight delivery was impossible. He sat for a long while wondering why. Why couldn’t there be reliable overnight mail delivery service? He decided to design one. Smith did just that and turned his design into a class project. His business professor gave him only a C for efforts. However, Smith refined the idea in that class project and eventually turned it into one of the first and most successful overnight mail services in the world——FedEx.
81. What did Masaru Ibuka’s idea turn out to be? （no more than 2 words）
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82. What did Fred Smith’s teacher think of his class project? （no more than 8 words）
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83. From what idea did Bill Bowerman make Nike athletic shoes ？（no more than 9 words）
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84. What is the main idea of the passage? （no more than 12 words）
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