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一、一堂数学课在一堂数学课上,教师问学生:“什么样的x能使不等式 2+5x>17成立?”等了一会又说:“谁知道的举手。”很多学生举了手。教师问一个没有举手的同学:“王健,你知道吗?”王健站起来答道:“不知道。”教师:“x=1行不行?”王健:“不行,2+5×1=7,不大于17。”教师:“x=2行不行?”王健:“也不行。”教师:“x=3行不行?”王健:“还不行。2+5×3=17,还不是大于17。”教师:“那么怎样的x才行呢?”王健:“只要比3大一些的数就行了。”教师:“怎样表示出来呢?”王健:“写成x>3。”教师:“对了。你能从2+5x>17推出x>3来吗?”王健想了一会说:“不知道。”教师:“把这里的大于号改成等号,就得到一个方程,2+5x=17。什么样的x能使这个方程成立呢?”王健想了一会说:“x=3”。教师:“你是怎样从2+5x=17推出x=3来的?”王健:“解方程呀!”教师:“怎样
First, a math lesson In a math lesson, the teacher asked the student: “What kind of x can make the inequality 2+5x>17 be established?” Waited for a while and said: “Who knows how to raise his hand.” Many students held hand. The teacher asked a classmate who did not raise his hand: “Wang Jian, you know?” Wang Jian stood up and replied, “I don’t know.” Teacher: “Is it OK if x=1?” Wang Jian: “No, 2+5× 1=7, no more than 17. “Teacher: ”Isn’t x=2?“ Wang Jian: ”No.“ Teacher: ”Isn’t x=3?“ Wang Jian: ”Not yet. 2+5×3= 17, is not greater than 17. “Teacher:” So what kind of x Caixing it? “Wang Jian:” As long as the number is bigger than 3 on the line. “Teacher:” How to show it? “Wang Jian:” written as x >3.“ Teacher: ”Yes. Can you launch x>3 from 2+5x>17?“ Wang Jian thought for a moment and said, ”I don’t know.“ Teacher: ”Change the greater number here to The number, you get an equation, 2+5x = 17. What kind of x can make this equation?” Wang Jian thought for a moment and said: “x=3”. Teacher: “How did you get x=3 from 2+5x=17?” Wang Jian: “Solve the equation!” Teacher: "How