64 nha bn

2^0.2^9:2^3

=2^9:2^3

=2^6=64

 k mik nha

2^0 x 2^9 : 8 

= 1 x 512 : 8 

= 64

nha bạn 

Bằng 64

vì 2X2X2X2X2=32

 2 mũ 5 =  2x2x2x2x2=32

=>32=2 mũ 5

HT

(có thể lm ngược lại nha bn) 

\(S=\frac{1}{4}+\frac{1}{28}+\frac{1}{70}+\frac{1}{130}+...+\frac{1}{10300}\)

\(=\frac{1}{1.4}+\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}+...+\frac{1}{100.103}\)

\(=\frac{1}{3}\left(\frac{3}{1.4}+\frac{3}{4.7}+\frac{3}{7.10}+\frac{3}{10.13}+...+\frac{3}{100.103}\right)\)

\(=\frac{1}{3}\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}+...+\frac{1}{100}-\frac{1}{103}\right)\)

\(=\frac{1}{3}\left(1-\frac{1}{103}\right)\)

\(=\frac{34}{103}\)

\(\frac{2}{7.8}+\frac{2}{8.9}+...+\frac{2}{57.58}=2\left(\frac{1}{7.8}+\frac{1}{8.9}+...+\frac{1}{57.58}\right)\)

\(=2\left(\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+...+\frac{1}{57}-\frac{1}{58}\right)\)

\(=2\left(\frac{1}{7}-\frac{1}{58}\right)=\frac{2.51}{406}=\frac{51}{203}\)

\(A=154.158=\left(156-2\right)\left(156+2\right)=156.156-2.156+2.156-2.2\)

\(=156.156-4=B-4\)

Do đó \(A< B\).

Gọi hai số cần tìm là \(a,b\)(\(a\ge b\ge1\))

Vì \(\left(a,b\right)=7\)nên ta đặt \(a=7m,b=7n\)(\(\left(m,n\right)=1,m\ge n\ge1\))

\(a+b=7m+7n=28\Leftrightarrow m+n=4\)

mà \(\left(m,n\right)=1,m\ge n\ge1\)nên \(m=3,n=1\).

Suy ra \(a=7.3=21,b=7.1=7\).

a)Co bi sai de ko vay ha ban 

ukm cong nhan