зная что а+b=6 и а^3+b^3=72,найдите аb
а+b=6 и а^3+b^3=72
а^3+b^3=(a+b)(a^2-ab+b^2)=6*(a^2-ab+b^2)
(a+b)^2=a^2+2ab+b^2=36
a^2+b^2=36-2ab
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а+b=6 и а^3+b^3=72
а^3+b^3=(a+b)(a^2-ab+b^2)=6*(a^2-ab+b^2)
(a+b)^2=a^2+2ab+b^2=36
a^2+b^2=36-2ab
6*(36-2ab-ab)=7236-3ab=12ab=24/3=8