Question

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Answer 1

$( \frac{1}{4} y - 2z) {}^{2}$
$( \frac{1}{4} y) {}^{2} - 2 \times \frac{1}{4} y \times 2z + (2z) {}^{2}$
$\frac{1}{16} y {}^{2} - yz + 4z {}^{2}$