Bài 25:
$a)E=\frac{3^{9}.3^{20}.2^{8}}{3^{24}.243.2^{6}}$
$E=\frac{3^{29}.2^{8}}{3^{24}.3^{5}.2^{6}}$
$E=\frac{3^{29}.2^{8}}{3^{29}.2^{6}}$
$E=\frac{2^{8}}{2^{6}}$
$E=2^{2}=4$
$B)F=\frac{2^{15}.5^{3}.2^{6}.3^{4}}{8.2^{18}.81.5}$
$F=\frac{2^{21}.5^{3}.3^{4}}{2^{3}.3^{4}.2^{18}.5}$
$F=\frac{2^{21}.5^{3}.3^{4}}{2^{21}.3^{4}.5}$
$F=\frac{5^{3}}{5}$
$F=5^{2}=25$
Baif 24:
$a)\frac{1}{5.6}+\frac{1}{6.7}+...+\frac{1}{24.25}$
$=\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{24}-\frac{1}{25}$
$=\frac{1}{5}-\frac{1}{25}$
$=\frac{4}{25}$
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