Question

A=1/1,4+1/4,7+1/7,10+...+1/40,43+1/43,46

Giup em bai nay nha, cam on ?

 

Answer 1

\(\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+...+\frac{1}{40.43}+\frac{1}{43.46}\)

\(=3.\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{43}-\frac{1}{46}\right)\)

\(=3.\left(1-\frac{1}{46}\right)\)

\(=3.\frac{45}{46}\)

\(=\frac{135}{46}\)

~Học tốt~

Answer 2

\(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+....+\frac{3}{40.43}+\frac{3}{43.46}\)

\(=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+...+\frac{1}{40}-\frac{1}{43}+\frac{1}{43}-\frac{1}{46}\)

\(=1-\frac{1}{46}\)

\(=\frac{45}{46}\)

~ Hok tốt ~

Answer 3

em cam on