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Daca x-y=3 si x la patrat - y la patrat = 12 , determinati numarul a = ( x+y) + ( x+y) la patrat + ( x + y ) la a treia .

Răspuns :

x-y=3
x²-y²=12
(x-y)(x+y)=x²-y²
3(x+y)=12
x+y=12/3
x+y=4
(x+y) +(x+y)²+(x+y)³=4+4²+4³=4+16+64=20+64=84