a5+b5?a+b=1 a²+b²=2
3个回答
ab=0.5
a3+b3=1*(2-0.5)=1.5
(a3+b3)(a2+b2)=S+(a2b2)(a+b)=S+0.25
1.5*2=S+0.25
S=2.75
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