Bài 2. Làm tính nhân

a) \(-6 \cdot \left(-\frac{2}{3}\right) \cdot 0,25\)

b) \(\frac{15}{4} \cdot \left(-\frac{7}{15}\right) \cdot \left(-\frac{2}{5}\right)\)

c) \(\left(-\frac{2}{5}\right) \cdot \left(-\frac{9}{11}\right) \cdot \left(-\frac{1}{14}\right) \cdot \frac{2}{5}\)

d) \(\left(-5 \cdot \frac{1}{2}\right) \cdot \left(-\frac{1}{2}\right) \cdot \left(\frac{2}{3}\right) \cdot \left(\frac{2}{3}\right)\)

e) \(\left(\frac{1}{4}\right) \cdot \left(-\frac{8}{15}\right) \cdot \frac{3}{5} \cdot \frac{2}{5} \cdot \left(\frac{3}{4}\right)\)

f) \(\left(-0,125\right) \cdot \left(-16\right) \cdot \left(\frac{8}{9}\right) \cdot \left(-0,25\right)\)

Hãy cùng giải từng bài toán:

a) \(-6 \cdot \left(-\frac{2}{3}\right) \cdot 0,25\)
\[ = -6 \cdot -\frac{2}{3} \cdot 0,25 \]
\[ = 6 \cdot \frac{2}{3} \cdot 0,25 \]
\[ = 6 \cdot \frac{2}{3} \cdot \frac{1}{4} \]
\[ = 6 \cdot \frac{2}{12} \]
\[ = 6 \cdot \frac{1}{6} \]
\[ = 1 \]

b) \(\frac{15}{4} \cdot \left(-\frac{7}{15}\right) \cdot \left(-\frac{2}{5}\right)\)
\[ = \frac{15}{4} \cdot -\frac{7}{15} \cdot -\frac{2}{5} \]
\[ = \frac{15 \cdot -7 \cdot -2}{4 \cdot 15 \cdot 5} \]
\[ = \frac{210}{300} \]
\[ = \frac{7}{10} \]

c) \(\left(-\frac{2}{5}\right) \cdot \left(-\frac{9}{11}\right) \cdot \left(-\frac{1}{14}\right) \cdot \frac{2}{5}\)
\[ = -\frac{2}{5} \cdot -\frac{9}{11} \cdot -\frac{1}{14} \cdot \frac{2}{5} \]
\[ = \frac{2 \cdot 9 \cdot 1 \cdot 2}{5 \cdot 11 \cdot 14 \cdot 5} \]
\[ = \frac{36}{385} \]

d) \(\left(-5 \cdot \frac{1}{2}\right) \cdot \left(-\frac{1}{2}\right) \cdot \left(\frac{2}{3}\right) \cdot \left(\frac{2}{3}\right)\)
\[ = -\frac{5}{2} \cdot -\frac{1}{2} \cdot \frac{2}{3} \cdot \frac{2}{3} \]
\[ = \frac{5}{2} \cdot \frac{1}{2} \cdot \frac{2}{3} \cdot \frac{2}{3} \]
\[ = \frac{5 \cdot 1 \cdot 2 \cdot 2}{2 \cdot 2 \cdot 3 \cdot 3} \]
\[ = \frac{20}{36} \]
\[ = \frac{5}{9} \]

e) \(\left(\frac{1}{4}\right) \cdot \left(-\frac{8}{15}\right) \cdot \frac{3}{5} \cdot \frac{2}{5} \cdot \left(\frac{3}{4}\right)\)
\[ = \frac{1}{4} \cdot -\frac{8}{15} \cdot \frac{3}{5} \cdot \frac{2}{5} \cdot \frac{3}{4} \]
\[ = \frac{1 \cdot -8 \cdot 3 \cdot 2 \cdot 3}{4 \cdot 15 \cdot 5 \cdot 5 \cdot 4} \]
\[ = \frac{-144}{600} \]
\[ = -\frac{6}{25} \]

f) \(\left(-0,125\right) \cdot \left(-16\right) \cdot \left(\frac{8}{9}\right) \cdot \left(-0,25\right)\)
\[ = -0,125 \cdot -16 \cdot \frac{8}{9} \cdot -0,25 \]
\[ = 0,125 \cdot 16 \cdot \frac{8}{9} \cdot 0,25 \]
\[ = 2 \cdot \frac{8}{9} \cdot 0,25 \]
\[ = \frac{16}{9} \cdot 0,25 \]
\[ = \frac{16}{9} \cdot \frac{1}{4} \]
\[ = \frac{16}{36} \]
\[ = \frac{4}{9} \]

Vậy các kết quả là:
a) 1
b) \(\frac{7}{10}\)
c) \(\frac{36}{385}\)
d) \(\frac{5}{9}\)
e) \(-\frac{6}{25}\)
f) \(\frac{4}{9}\)