Question

Tính nhanh     E =    3/2.5 + 3/5.8 + 3/8.11 + ..... + 3/29.32

 Giaỉ nhanh giúp m\k nha cần gấp lắm !

 

Answer 1

= 1/2 - 1/5 + 1/5 - 1/8 + 1/8 - 1/11 + .... + 1/29 - 1/32

= 1/2 - 1/32

= ..... ( tự bấm máy tính nhé )

Answer 2

Ta có: \(E=\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+....+\frac{1}{29}-\frac{1}{32}\)

     \(\Rightarrow E=\frac{1}{2}-\frac{1}{32}\)

     \(\Rightarrow E=\frac{16-1}{32}=\frac{15}{32}\)

 Vậy \(E=\frac{15}{32}\)

Answer 3

E=5-2/2×5 + 8-5/5×8+11-8/8×11+.....+32-29/29×32

E=1/2-1/5+1/5-1/8+1/8-1/11+......+1/29-1/32

E=1/2-1/32

E=15/32