100 x 9 + 100 x 91 x 30 - 21

= 100 x ( 9 + 91 x 30 ) - 21

= 273900 - 21

= 273879

100 x 9 + 100 x 91 x 30 - 21

= 100 x ( 9 + 91 ) x 30 - 21

= 100 x 100 x 30 - 21

= 10 000 x 30 - 21

= 300 000 - 21

= 299 979

_Học _ tốt_

273879

\(\frac{7}{10}+\frac{91}{100}+\frac{37}{1000}+\frac{547}{1000}+\frac{728}{1000}=\frac{651}{200}\)

\(\frac{7}{10}+\frac{91}{100}+\frac{37}{100}+\frac{547}{1000}+\frac{728}{1000}\)

\(=\frac{651}{200}\)

Chúc bạn học tốt ~

\(\frac{7}{10}+\frac{91}{100}+\frac{37}{100}+\frac{547}{1000}+\frac{728}{1000}=\frac{700}{1000}+\frac{910}{1000}+\frac{370}{1000}+\frac{547}{1000}+\frac{728}{1000}=\)

\(=\frac{700+910+370+547+728}{1000}=\frac{3255}{1000}=3,255\)

e) Từ 91 đến 100: 91, 92, 93, 94, 95, 96, 97, 98, 99, 100.

=(1+100).100:2

=101.100:2

=10100:2

=5050

kết quả ra 570 nha bạn

258 + 385 - 158 - 115 + 91 + 9 + 100

= ( 258 - 158 ) + ( 385 - 115 ) + ( 91 + 9 ) + 100

= 100 + 270 + 100 + 100

= 100 x 3 + 270

= 300 + 270

= 570

(x+100)*(1/99+1/96+1/93+1/91)=0

suy ra x+100=0

suy ra x=-100

từ sai

là từ :sai nha bn

là từ sai.

\(\text{Ư}\left(91\right)=\left\{1;3;17;91\right\}\)

\(\text{Ư}\left(100\right)=\left\{1;2;4;5;10;20;25;50;100\right\}\)