Question

Tính nhanh tổng sau: A= 1/20 + 1/30 + 1/42 + 1/56 + 1/72 + 1/90 

Answer 1

A=1/20+1/30+1/42+1/56+1/72+1/90

A=1/4x5+1/5x6+1/6x7+1/7x8+1/8x9+1/9x10

A=1/4-1/5+1/5-1/6+...+1/9-1/10

A=1/4-1/10

A=3/20

 

Answer 2

Ban oi,toan nay khong phai toan lop 4

Answer 3

Ban oi,toan nay khong phai lop 4

Answer 4

\(A=\frac{1}{4\times5}+\frac{1}{5\times6}+\frac{1}{6\times7}+\frac{1}{7\times8}+\frac{1}{8\times9}+\frac{1}{9\times10}\)

\(=\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}\)

\(=\frac{1}{4}-\frac{1}{10}=\frac{5-2}{20}=\frac{3}{20}\)

Answer 5

=\(\frac{3}{20}\)

Answer 6

day khong phai toan lop 4

Answer 7

3/20 nha Phạm Ngọc Nam Phương

Answer 8

\(\frac{3}{20}\)

Answer 9

\(\frac{3}{20}\)

Answer 10

A=1/4*5+1/5*6+1/6*7+1/7*8+1/8*9+1/9*10

A=1/4-1/5+1/5-1/6+1/6-1/7+1/8-1/9+1/9-1/10

A=1/4-(1/5-1/5)+(1/6-1/6)+(1/7-1/7)+(1/8-1/8)+(1/9-1/9)-1/10

A=1/4-1/10+0+0+0+0+0

A=3/20

Cho xin cái đúng nhé<.>

Answer 11

3/20

Bạn nhớ tích cho mình nha

Answer 12

A=1/20+ 1/30+ 1/42+ 1/56+ 1/72+ 1/90

A=1/4x5+1/5x6+1/6x7+1/7x8+1/8x9+1/9x10

A=1/4- 1/5 + 1/5 - 1/6 + 1/7 + 1/8 + 1/9 - 1/10

A=1/4-  1/10

A=3/20