496.- a) lg 8+1g 18 2 lg 2+lg 3 ;

a) $$\frac{lg 8 + lg 18}{2 lg 2 + lg 3} = \frac{lg (8 \cdot 18)}{lg (2^2 \cdot 3)} = \frac{lg (2^3 \cdot 2 \cdot 3^2)}{lg (4 \cdot 3)} = \frac{lg (2^4 \cdot 3^2)}{lg (12)} = \frac{lg (16 \cdot 9)}{lg 12} = \frac{lg 144}{lg 12} = \frac{lg 12^2}{lg 12} = \frac{2 lg 12}{lg 12} = 2$$

Ответ: 2