Question

помогите, пожалуйста​

Answer 1

$\frac{ {1.8}^{2} - {1.2}^{2} }{ {4.2}^{2} - 2 \times 4.8 \times 4.2 + {4.8}^{2} } = \frac{(1.8 - 1.2)(1.8 + 1.2)}{(4.8 - 4.2) {}^{2} } = \\ = \frac{0.6 \times 3}{(0.6) {}^{2} } = \frac{3}{0.6} = \frac{30}{6} = 5$