$\textit{Đáp án + giải thích bước giải}$
$\text{a) $34^{2}$ + $66^{2}$ + 66 . 68}$
$\text{= $34^{2}$ + $66^{2}$ + 2.34.66}$
$\text{= $(34 + 66)^{2}$}$
$\text{= $100^{2}$}$
$\text{10 000}$
$\text{b) $74^{2}$ + $24^{2}$ - 48.74}$
$\text{= $74^{2}$ + $24^{2}$ - 2.24.74}$
$\text{= $(74 - 24)^{2}$}$
$\text{= $50^{2}$}$
$\text{= 2 500}$