\(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+......+\frac{1}{97}-\frac{1}{99}=\frac{1}{3}-\frac{1}{99}=\frac{32}{99}\)
\(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+......+\frac{1}{97}-\frac{1}{99}=\frac{1}{3}-\frac{1}{99}=\frac{32}{99}\)
Tính B=1*3+5*7+9*11+...+97*101
C=1*3*5-3*5*7+5*7*9-....-97*99*101
D=1*99+3*97+5*95+...+49*51
E=1*3^3+3*5^3+5*7^3+...+49*51^3
F=1*99^2+2*98^2+3*97^2+...+49*51^2
m=2/3*5+2/5*7+2/7*9+.........+2/97*99
n=3/5*7+3/7*9+3/9*11+........+3/197*199
2/ 3×5 +2/ 5×7+2/ 7×9+2/ 97×99 = ?
CMR: 2/3*5 + 2/5*7 + 2/7*9 +...+ 2/97*99 > 8/25
Chứng minh :
2/3×5+2/5×7+2/7×9+...+2/97×99>32%
A=1-2-3-4=5-6-7-8+9-10-11-12+...+97-98-99-100
B=1+2-3-4+5+6-7-8+....+97+98-99-100
TÍNH NHANH
1) S= 1/1*2+1/2*3+1/3*4+...+1/99*100
2) S= 3/1*3+3/3*5+2/5*7+...+2/97*99
3) S= 4/5*7+4/7*9+4/9*11+...+4/59*61
M=2/3*5*7+2/3*7*9+......+2/3*97*99
cách làm nha
thực hiện phép tính :
a, A=1-3-5-7-9-11-13-15-...-97-99
b,B=1+3-5-7+9+11-13-15+...-97-99
c,C=1-3-5+7+9-11-13+15+...+97-99
d,D=-(5)-(2-7)-(5-12)-(4-6)-(-3)
mk đang cần gấp giúp mk vs nha cảm ơn nhìu