Re: [問題] 一題數學

[klode (...)]

※ 引述《Rivera01 (MO Rivera)》之銘言：
:   If a + b = 3 and a2 + b2 = 7, then what is the value of a4 + b4?
 (a+b)^2=a^2+b^2+2ab 所以 2ab=3^2-7=2,ab=1 故(ab)^2=1

 (a^2+b^2)^2=a^4+b^4+2(ab)^2 所以a^4+b^4=7^2-2=47

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