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根式問題,,,,,,...........
發問:
√49=7 49的開方根=+7/-7 對嗎 更新: 請按"我" 回答其他數學 更新 2: 其實我係想問√49係唔只係等於7,而-7係唔係唔岩的
最佳解答:
Although 7^2 = 49 and (-7)^2 = 49 √49=7 only. This is because the symbol "√ " means "positive square root" How about -7? -7 = -√49 Furthermore, in solving equations with radical signs, we have to reject the answer √x = n. where n is any negative number. Because a positive square root is never a negative number. eg: x - √x - 12 = 0 (√x - 4)(√x + 3) = 0 √x = 4or√x = -3 (rejected) x = 16 only. 2007-08-06 17:22:31 補充： Plus, eg.x^2 = 49x = √49orx = -√49------ This step, so we can generate:x = 7 orx = -7But not :x = √49x = 7(orx = -7 ----- This part can't be generated by √49)
其他解答:
ya you are right|||||Right!Right!|||||對 因為負負得正,正正都得正
根式問題,,,,,,...........
發問:
√49=7 49的開方根=+7/-7 對嗎 更新: 請按"我" 回答其他數學 更新 2: 其實我係想問√49係唔只係等於7,而-7係唔係唔岩的
最佳解答:
Although 7^2 = 49 and (-7)^2 = 49 √49=7 only. This is because the symbol "√ " means "positive square root" How about -7? -7 = -√49 Furthermore, in solving equations with radical signs, we have to reject the answer √x = n. where n is any negative number. Because a positive square root is never a negative number. eg: x - √x - 12 = 0 (√x - 4)(√x + 3) = 0 √x = 4or√x = -3 (rejected) x = 16 only. 2007-08-06 17:22:31 補充： Plus, eg.x^2 = 49x = √49orx = -√49------ This step, so we can generate:x = 7 orx = -7But not :x = √49x = 7(orx = -7 ----- This part can't be generated by √49)
其他解答:
ya you are right|||||Right!Right!|||||對 因為負負得正,正正都得正
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