a) 24²-12² 18²-6²;

a) $$ \frac{24^2 - 12^2}{18^2 - 6^2} = \frac{(24 - 12)(24 + 12)}{(18 - 6)(18 + 6)} = \frac{12 \cdot 36}{12 \cdot 24} = \frac{36}{24} = \frac{3}{2} = 1,5$$

Ответ: 1,5