Uỷnh đồ si - ra cái gì ra cái này
15+20-30=1)...+8-9=2)...
45-8+12=3)...-49=4)...
1)...+2)...+3)...+4)...=...
bạn nào biết câu này nghĩa là gì mình cho kết bạn với mình luôn
CÂU1:/1+1+1+1+1+1+1+1+1+1+2+2+2+2+2+2+2+2+2+2+3+3+3+3+3+3+3+3+3+3+4+4+4+40+10+20+30+40+50+60+70+80+90+100=?
CÂU2:/ ????????????????????????????????????????????????????????????+???????????????????????????????????????+???????????????????????????????????????????+?10?????????????+?????????????????????????=.........?
1+2+3+4+1+2+3+4-10-20=
ai kết bạn thì mình tick cho
1+2+3+...+20=?
1+2+3+...+20
e,\(A=\frac{1}{2}+\frac{5}{6}+\frac{11}{12}+\frac{19}{20}+\frac{29}{30}+\frac{41}{42}=\left(1-\frac{1}{2}\right)+\left(1-\frac{1}{6}\right)+\left(1-\frac{1}{12}\right)+\left(1-\frac{1}{20}\right)+\left(1-\frac{1}{20}\right)+\left(1-\frac{1}{42}\right)\)
\(\Rightarrow A=1-\frac{1}{2}+1-\frac{1}{6}+1-\frac{1}{12}+1-\frac{1}{20}+1-\frac{1}{30}+1-\frac{1}{42}=4-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}\right)\)
\(\Rightarrow A=4-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}\right)=4-\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}\right)\)
\(\Rightarrow A=4-\left(\frac{1}{1}-\frac{1}{7}\right)=4-\frac{6}{7}=3\frac{1}{7}\)
Cho 1+1 = 2
2+2 = 6
3+3 = 12
4+4 = 20
10+10 = ?
1 + 2 + 3 + 4 + ..........+20 = ?
1+2+3+...+19+20
7/2.x-3/4=5/6– -2/3
5/6-(20%.x-3/4)=x+1/2
