F1 Упростите выражение: 4 1)ab; 15 11 2) 6x1y 45 13 3) d32c; 24 9 3 11 13 4) 18a1bc.

1) $$\frac{5}{8}a \cdot \frac{4}{15}b = \frac{5 \cdot 4}{8 \cdot 15}ab = \frac{20}{120}ab = \frac{1}{6}ab$$

Ответ: $$\frac{1}{6}ab$$

2) $$6\frac{3}{4}x \cdot 1\frac{11}{45}y = \frac{6 \cdot 4 + 3}{4}x \cdot \frac{1 \cdot 45 + 11}{45}y = \frac{27}{4}x \cdot \frac{56}{45}y = \frac{27 \cdot 56}{4 \cdot 45}xy = \frac{1512}{180}xy = \frac{42}{5}xy = 8\frac{2}{5}xy$$

Ответ: $$8\frac{2}{5}xy$$

3) $$\frac{13}{24}d \cdot 32c = \frac{13 \cdot 32}{24}dc = \frac{13 \cdot 4}{3}dc = \frac{52}{3}dc = 17\frac{1}{3}dc$$

Ответ: $$17\frac{1}{3}dc$$

4) $$18\frac{1}{3}a \cdot 1\frac{2}{11}b \cdot \frac{9}{13}c = \frac{18 \cdot 3 + 1}{3}a \cdot \frac{1 \cdot 11 + 2}{11}b \cdot \frac{9}{13}c = \frac{55}{3}a \cdot \frac{13}{11}b \cdot \frac{9}{13}c = \frac{55 \cdot 13 \cdot 9}{3 \cdot 11 \cdot 13}abc = \frac{5 \cdot 1 \cdot 3}{1 \cdot 1 \cdot 1}abc = 15abc$$

Ответ: $$15abc$$