Question

CMR các tổng sau không là số tự nhiên a)A=1/2+1/3+1/4 b)B=1/2+1/3+...+1/8 c)C=1/2+1/3+1/4+...+1/16

Answer 1

:v sao đen thùi lùi dị 

Answer 2

\(A=\dfrac{6}{12}+\dfrac{4}{12}+\dfrac{3}{12}\\ A=\dfrac{13}{12}\\ B=\left(\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}\right)+\left(\dfrac{1}{3}+\dfrac{1}{6}\right)+\left(\dfrac{1}{5}+\dfrac{1}{7}\right)\\ B=\left(\dfrac{4}{8}+\dfrac{2}{8}+\dfrac{1}{8}\right)+\left(\dfrac{2}{6}+\dfrac{1}{6}\right)+\left(\dfrac{7}{35}+\dfrac{5}{35}\right)\\ B=\dfrac{7}{8}+\dfrac{3}{6}+\dfrac{12}{35}\\ B=\dfrac{7}{8}+\dfrac{1}{2}+\dfrac{12}{35}\\ B=\dfrac{11}{8}+\dfrac{12}{35}\\ B=\dfrac{481}{280}\)

Answer 3

Đề bài ở dưới bình luận Nguyễn acc 2 ý ~ kk ^_^