\(D=\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{97.99}\)
\(\Rightarrow D=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{99}\)
\(\Rightarrow D=\frac{1}{3}-\frac{1}{99}=\frac{33}{99}-\frac{1}{99}=\frac{32}{99}\)
P/S : dấu . là dấu nhân nha
1+2-3-4+5+6-7-8+9+...+97+98-99-100+101+102
Tính bằng cách thuận tiện nhất
1,1+1,2+1,3+...+1,7+1,8+1,9=
1+2+3+4+...+97+98+99+100=
1+3+5+7+9+...+93+95+97+99=
tinh
2+4+6+8+10+...+98+100
1+3+5+7+9+...+97+99
Thực hiện phép tính :
2/1×3+2/3×5+2/5×7+...+2/97×99
2 + 4 + 6 + ................... + 2018
2/1×3 + 2/3×5 + 2/5×7 + .................. + 2/97 ×99
Giải giúp mình nha !
tinh nhanh
1+2+3+4+5+6+7+8+9+10+....+90+91+92+93+94+95+96+97+98+99
(1 + \(\dfrac{2}{5}\)) x (1 + \(\dfrac{2}{7}\)) x (1 + \(\dfrac{2}{9}\)) x (1 + \(\dfrac{2}{11}\)) x.......x (1 + \(\dfrac{2}{97}\)) x (1 + \(\dfrac{2}{99}\))
Tính nhanh:
37 x 27 + 63 x 27
1+2+3+4+...+97+98+99
1+2+3+4+5+6+7+8+9+10
1-2+3-4+5-6+7-8+................+97-98+99
