3.45 Решите пропорцию: a) 13.7 : 9; 4 3,6 B) 15 : 6.3 a+ 0.03 0.21 6) 1/a:6-14:0.7: r) 4 : 2,5-1 (0.4+ b). г)

a) $$13.7/4 = 9/3.6$$

$$13.7 \cdot 3.6 = 4 \cdot 9$$

$$49.32 = 36$$ - неверно.

б) $$1.5/(a+0.03) = 6.3/0.21$$

$$1.5 \cdot 0.21 = 6.3(a+0.03)$$ $$0.315 = 6.3a + 0.189$$ $$6.3a = 0.315-0.189$$ $$6.3a = 0.126$$ $$a = 0.126/6.3$$ $$a = 0.02$$

б) $$1/a:6 = 14:0.7$$

$$1/a \cdot 0.7 = 6 \cdot 14$$

$$0.7/a = 84$$

$$a = 0.7/84 = 1/120 \approx 0.0083$$

г) $$4/5 : 2.5 = 1 \frac{1}{2} : (0.4 + b)$$

$$0.8 : 2.5 = 1.5 : (0.4 + b)$$

$$0.8 \cdot (0.4 + b) = 2.5 \cdot 1.5$$

$$0.32 + 0.8b = 3.75$$

$$0.8b = 3.43$$

$$b = 3.43/0.8 = 4.2875$$

Ответ: а) пропорция неверна; б) $$a = 0.02$$, в) $$a = 1/120 \approx 0.0083$$, г) $$b = 4.2875$$