Question

Bài 1: Tính hợp lý. (nếu có thể)
A= 1/10+1/40+1/88+1/154+1/238+1/340
B=2 +1/547 . 3/211 - 546/547 - 4/547.211
D= 1/3+1/6+1/12+1/24+1/48
E= 1/2 - 1/4 + 1/8 - 1/16 +...+ 1/2048
F= 0,5 - 1/3 - 0,4 -5/7 - 1/6 + 4/35 - 1/41

Answer 1

Giải:

A=1/10+1/40+1/88+1/154+1/238+1/340

A=1/2.5+1/5.8+1/8.11+1/11.14+1/14.17+1/17.20

A=1/2-1/5+1/5-1/8+1/8-1/11+1/11-1/14+1/14-1/17+1/17-1/20

A=1/2-1/20

A=9/20

D=1/3+1/6+1/12+1/24+1/48

D=1/3+1/2.3+1/3.4+1/4.6+1/6.8

D=1/3+1/2-1/3+1/3-1/4+1/2.(2/4.6+2/6.8)

D=1/3+1/2-1/4+1/2.(1/4-1/6+1/6-1/8)

D=1/3+1/4+1/2.(1/4-1/8)

D=1/3+1/4+1/2.1/8

D=1/3+1/4+1/16

D=31/48

F=0,5-1/3-0,4-4/7-1/6+4/35-1/41

F=1/2-1/3-2/5-4/7-1/6+4/35-1/41

F=1/6-(-6/35)-1/6+4/35-1/41

F=(1/6-1/6)+(6/35+4/35)-1/41

F=0+2/7-1/41

F=2/7+1/41

F=75/287

Chúc bạn học tốt!