Question

. Вычислите рациональным способом
$\frac{ {38}^{2} - {17}^{2} }{ {47}^{2} - {19}^{2} }$
​

Answer 1

Ответ:

$\frac{ { 38}^{2} - {17}^{2} }{ {47}^{2} - {19}^{2} } = \frac{(38 - 17)(38 + 17)}{(47 - 19)(47 + 19)} = \\ \frac{21 \times 55}{28 \times 66} = \frac{3 \times 5}{4 \times 6} = \frac{15}{24} = \frac{5}{6}$