`1/10+2/20+3/30+4/40+5/50+6/60+7/70+8/80+9/90`

`=1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10`

`=1/10xx9`

`=9/10`

giúp mình bài này nha

a,đề bài

=1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10

=9/10

Phép tính:1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10 là rút gọn lần lượt cho 2,3,4,5,6,7,8,9 nha

\(\frac{1}{10}+\frac{2}{20}+\frac{3}{30}+\frac{4}{40}+\frac{5}{50}+\frac{6}{60}+\frac{7}{70}+\frac{8}{80}+\frac{9}{90}\)

=\(\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}\)

=\(\frac{9}{10}\)

\(\frac{1}{10}+\frac{2}{20}+\frac{3}{30}+\frac{4}{40}+\frac{5}{50}+\frac{6}{60}+\frac{7}{70}+\frac{8}{80}+\frac{9}{90}=\frac{1}{10}+\frac{1}{10}+....+\frac{1}{10}=\frac{9}{10}\)

rút gọn mấy phân số trên thì còn

=1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10

=9x1/10

=9/10

\(\frac{1}{10}+\frac{2}{20}+\frac{3}{30}+\frac{4}{40}+\frac{5}{50}+\frac{6}{60}+\frac{7}{70}+\frac{8}{80}+\frac{9}{90}\)

\(=\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}\)

\(=\frac{1}{10}\times9\)

\(=\frac{9}{10}\)

=1/10 + 1/10 +...+ 1/10 ( có 9 phân số )

=9/10

1/10 + 1/20 + 3/30 + 4/40 + 5/50 + 6/60 + 7/70 + 8/80 + 9/90 ( có 9 phân số )

= 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 + 1/10 ( có 9 phân số 1/10 )

= 1/10 x 9

= 9/10

= 1/10+1/10+1/10+1/10+..+1/10 ( 9 số hạng)

= 9/10

Kết quả =9/10 nha,mình làm rùi

Tk nha Nguyễn Thị Thục Quyên

1/10+2/20+3/30+4/40+5/50+6/60+7/70+8/80+9/90

=1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10

=1/10 x 9 = 9/10

=7/70+7/70+7/70+7/70+7/70+7/70+7/70+7/70+7/70

=7/70*9/9

=63/630=1/10

 \(=\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+...+\frac{1}{10}\)có 9 p/số

\(=\frac{1}{10}.9=\frac{9}{10}\)

= 1/10 + 1/10 + ...................... + 1/10 có 9 phân số

= 1/10 x 9

= 9/10

ai tk mình mình đang bị âm điểm

9 / 12 bn nha

tk mk nha các bn

thanks nhiêu

1/10+2/20+3/30+4/40+5/50+6/60+7/70+8/80+9/90

=1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10

=1/10*9=9/10

9/10 nha

=1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10+1/10

=1/10x9

=9/10

9/10 nha

=\(\frac{1}{10}\cdot9\)

=\(\frac{9}{10}\)

\(\frac{1}{10}+\frac{12}{20}+\frac{3}{30}+\frac{4}{40}+\frac{5}{50}+\frac{6}{60}+\frac{7}{70}+\frac{8}{80}+\frac{9}{90}\)

\(=\frac{1}{10}+\frac{12}{20}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}\)

\(=\frac{1}{10}\times8+\frac{12}{20}\)

\(=\frac{4}{5}+\frac{12}{20}\)

\(=\frac{16}{20}+\frac{12}{20}=\frac{28}{20}=\frac{7}{5}\)

= 25 * 5 + 15 * 5 + 60 * 5 *1 ( tớ viết dấu sao thay dấu nhân ) 

=5*(25+ 15 + 60+ 1)

=5* 100

=500

428 x 12 - 428 x 2

= 428 x (12 - 2)

= 4280

Chỉ biết 2 câu đầu hoi

Chúc em học tốt tick cho chị nha

995 x 5 + 4 x 5 + 5

= 995 x 5 + 4 x 5 + 5 x 1

= ( 995 + 4 + 1 ) x 5

= 1000 x 5

= 5000

655 x 6 - 355 x 6

= ( 655 - 355 ) x 6

= 300 x 6

= 1800

25 x 5 + 15 x 5 + 60 x 5

= ( 25 + 15 + 60 ) x 5

= 100 x 5

= 500

428 x 97 + 428 x 2 + 428

= 428 x 97 + 428 x 2 + 428 x 1

= 428 x ( 97 + 2 + 1 )

= 428 x 100

= 42800