[tex]x=[2^{900}\cdot 2^{600}\cdot 2+2^{2000}:2^{300}]^2+2^{3004}\\
x=(2^{1501}+2^{1700})^2+2^{3004}=(2^{1501})^2(1+2^{199})^2+2^{3004}\\
x=2^{3002}(1+2^{199})^2+2^{3004}\\
x=2^{3002}(1+2^{200}+2^{398}+4)\\
x=2^{3002}(2^{200}+2^{398}+5)si\ nu \ este\ patrat\ perfect\\
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y=5\cdot3^{2000}(9-3-1)=(5\cdot 3^{1000})^2-\ patrat\ perfect.[/tex]
