{12×[(5+2)×3-19]}/[2 ^2 ×(4-2^0)]=
{12×[(5+2)×3-19]}/[2 ^2 ×(4-2^0)]=
$\{12×[(5+2)×3-19]\} ÷ [2^2×(4-2^0)]$ =
= $\{12×[7×3-19]\} ÷ [4×(4-1)]$ =
= $\{12×[21-19]\} ÷ [4×3]$ =
= $\{12×2\} ÷ 12$ =
= $ 24 ÷12$ =
= $2$
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{12×[(5+2)×3-19]}/[2 ^2 ×(4-2^0)]=
${12×[7×3-19]}/[4×(4-1)]=$
${12×[21-19]}/[4×3]=$
${12×2}/12=2$
Ricorda $a^0=1$