\(50\%.\frac{4}{3}.10.\frac{7}{35}.0,75\)
\(=\frac{1}{2}.\frac{4}{3}.10.\frac{7}{35}.\frac{3}{4}\)
\(=\left(\frac{1}{2}.10\right)\times\left(\frac{4}{3}.\frac{3}{4}\right).\frac{7}{35}\)
\(=5.1.\frac{7}{35}\)
\(=\frac{35}{35}=1\)
~ Hok tốt ~
\(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+...+\frac{3}{40.43}\)
\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{40}-\frac{1}{43}\)
\(=1+\left(\frac{1}{4}-\frac{1}{4}\right)+\left(\frac{1}{7}-\frac{1}{7}\right)+...+\left(\frac{1}{40}-\frac{1}{40}\right)-\frac{1}{43}\)
\(=1-\frac{1}{43}=\frac{42}{43}\)
~ Hok tốt ~
câu a) có trong đề cương của tui
