1.
a) \(3^4\times3^5\times3^6=3^{4+5+6}=3^{15}\)

b) \(5^2\times5^4\times5^5\times25=5^2\times5^4\times5^5\times5^2=5^{2+4+5+2}=5^{13}\)

c) \(10^8\div10^3=10^{8-3}=10^5\)

d) \(a^7\div a^2=a^{7-2}=a^5\)

2.

\(987=900+80+7\\ =9\times100+8\times10+7\\ =9\times10^2+8\times10^1+7\times10^0\)

\(2021=2000+20+1\\ =2\times1000+2\times10+1\times1\\ =2\times10^3+2\times10^1+1\times10^0\)

\(abcde=a\times10000+b\times1000+c\times100+d\times10+e\times1\\ =a\times10^4+b\times10^3+c\times10^2+d\times10^1+e\times10^0\)

còn bài 2

a ) 17 5 b ) 23 3 c ) − 27 3 . d ) − 19 8

a, ta có :

 \(\hept{\begin{cases}\frac{6}{7}< 1\\\frac{11}{10}>1\end{cases}}\Rightarrow\frac{6}{7}< \frac{11}{10}\)

b, ta có :

\(\hept{\begin{cases}\frac{-5}{7}< 0\\\frac{2}{7}>0\end{cases}}\Rightarrow\frac{-5}{7}>\frac{2}{7}\)

c, ta có :

\(\hept{\begin{cases}\frac{419}{-723}< 0\\\frac{-697}{-313}>0\end{cases}}\Rightarrow\frac{419}{-723}< \frac{-679}{-313}\)

a]6/7 va 11/10 

60/70 và 77/70 vay 11/10 lớn hơn 6/7 

a) \(\frac{6}{7}\) và \(\frac{11}{10}\)

Vì \(\frac{6}{7}< 1;1< \frac{11}{10}\)

\(\Rightarrow\frac{6}{7}< \frac{11}{10}\)

Vậy \(\frac{6}{7}< \frac{11}{10}\)

a,Ta có:

6/7< 1< 11/10

=> 6/7< 11/10

b,Ta có:

-5/17< 0< 2/7

=> -5/7< 2/7

a) \(7^{15}\)

b)\(162^8\).    2

c)\(10^8\)

d) \(a^0\)

Xin lỗi nha mk hơi vội nên có sai thì bạn châm trc cho mk nha.

\(2013=2.1000+10+3=2.10^3+1.10^1+3.10^0\)

\(20112013=2.10000000+100000+10000+2.1000+10+3\)

\(=2.10^7+10^5+10^4+2.10^3+10^1+3.10^0\)

2013 = 2 x 1000 + 10 + 3 = 2 x 10^3 + 1 . 10^1 + 3 . 10^0

20112013 = 2 x 10000000 + 100000 + 2 x 1000 + 10 + 3 =  2 x 10^7 + 10^5 + 10^4 + 2 x 10^3 + 10^1 + 3 x 10^0

ok nhé với lại 10^2 là 10 mũ 2 nhé =>

8=2^3    ;      20=20^1    ;    60=60^1    ;    90=90^1

16=2^4  ;      27=3^3      ;    81=3^4      ;    100=10^2

a)  a b c =   a . 100   +   b . 100   +   c . 1   =   a . 10 2   + b .   10 1 +   c . 10 0

b)  a b c d ¯ =   a . 1000   +   b . 100   +   c . 10   +   d   =   a . 10 3   +   b . 10 2   +   c . 10 1   +   d . 10 0