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Gọi A=1/5.8+1/8.11+1/11.14+...+1/605.608
A×3=3/5.8+3/8.11+3/11.14+...+3/605.608
A×3=1/5-1/8+1/8-1/11+1/11-1/14+...+1/605-1/608
A×3=1/5-1/608
A×3=603/3040
A=603/3040÷3
A=201/3040
Tính nhanh
a) 2/1.4+2/4.7+2/7.10+...+2/91.94+2/94.97
b) 1/5.8+1/8.11+1/11.14+...+1/605.608
(2/1.4=2 trên 1.4; 1/5.8=1 trên 5.8)
Ai lm đc nhớ nghi lời, cách giải đầy đủ
Cảm ơn!!!
Tính
A) \(\frac{1}{5.8}\)+\(\frac{1}{8.11}\)+\(\frac{1}{11.14}\)+...+\(\frac{1}{605.608}\)
B) A=\(\frac{3}{2^2}\).\(\frac{8}{3^2}\).\(\frac{15}{4^2}\)....\(\frac{899}{30^2}\)
1/5.8+1/8.11+1/11.14+...+1/x(x+3)=27/480
Tìm x 1/5.8+1/8.11+1/11.14+...+1/x.(x+3)=98/1545
Tính S
S=1/2.5+1/5.8+1/8.11+1/11.14+1/14.17+1/17.20
TÍNH
1/5.8+1/8.11+1/11.14+........+1/x(x+3)=101/1540
1/5.8+1/8.11=1/11.14+.....+1/x(x+3)= 101/1540
tính x biết: 1/5.8 + 1/8.11+1/11.14+ ....... +1/x(x+3)= 1 1991/1993
Tìm x biết:
1/5.8+1/8.11+1/11.14+......+1/x(x+3)=98/1545