Without finding the values of the 2 roots, by using sum & product of the roots, how can we find the values of x^2+y^2 ?
更新1:
Thanks for answering! But I'm a bit confused with the second step. How can x^2+ y^2 -> (x + y)² - 2xy ?
Thanks for answering! But I'm a bit confused with the second step. How can x^2+ y^2 -> (x + y)² - 2xy ?
收錄日期: 2021-04-21 22:20:20
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https://hk.answers.yahoo.com/question/index?qid=20110224000051KK00486