Question

A=1/2+1/6+1/12+1/20+1/42

ai làm được mình tk cho

Answer 1

Sai đề bài rồi

Answer 2

\(\frac{1}{2}\)+ \(\frac{1}{6}\) + \(\frac{1}{12}\)+ \(\frac{1}{20}\)+ \(\frac{1}{42}\)= \(\frac{173}{210}\)

Answer 3

xin loi sai de roi ban

Answer 4

Sửa đề :

\(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}\)

\(A=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}+\frac{1}{6\cdot7}\)

\(A=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{6}-\frac{1}{7}\)

\(A=1-\frac{1}{7}=\frac{6}{7}\)

Answer 5

thank