Bạn tham khảo :

Bài $2$ :

$a,$ 

$2^2 = 2.2 = 4$

$b,$

$3^3 = 3.3.3 = 27$

$c,$

$2^3 . 3^2 = 2.2.2 .3.3 = 8 . 9 = 72$

Bài $3$

$16 = 4^2$

$49=7^2$ 

$169 = 13^2$

Bài $4$

$a,$

$3^2 . 3^3 = 3^{2+3} = 3^5$

$b,$

$a^3.a^5 = a^{3+5} = a^8$

$c,$

$5^9:5^3 = 5^{9-3} = 5^6$

$d,$

$b^8:b^5=b^{8-5} = b^3$

$e,$

$3^5 . 9^4 = 3^5 . (3^2)^4 = 3^5 . 3^8 = 3^{5+8}=3^{13}$

$f,$

$49^3:7^4=(7^2)^3 : 7^4 = 7^6 : 7^4 = 7^{6-4} = 7^2$

Bài $5$

$a,$

$20+45:3^2$

$=20+45:9$

$=20+5$

$=25$

$b,$

$2^3 . 123 - 2^3 .23$

$=2^3.(123-23)$

$= 8 . 100$

$=800$

$c,$

$5^7:5^3+12.4.1^0$

$= 5^4 + 12.4.1$

$=5^4 +48$  

$= 625 + 48$

$= 673$ 

Bài 2:

a) 2² = 2 . 2 = 4

b) 3³ = 3 . 3 . 3 = 27

c) 2³ . 3² = 2 . 2 . 2 . 3 . 3 = 8 . 9 = 72

Bài 3:

a) 16 = 4 . 4 = 4²

b) 49 = 7 . 7 = 7²

c) 169 = 13 . 13 = 13²

Bài 4:

a) 3² . 3³ = $3^{2+3}$ = $3^{5}$

b) a³ . $a^{5}$ = $a^{3+5}$ = $3^{8}$

c) $5^{9}$ : 5³ = $5^{9-3}$ = $5^{6}$

d) $b^{8}$ : $b^{5}$ = $b^{8-5}$ = b³

e) $3^{5}$ . $9^{4}$ = $3^{5}$ . $(3²)^{4}$

                                   = $3^{5}$ . $3^{8}$ = $3^{13}$

f) $49^{3}$ : $7^{4}$ = (7²)³ : $7^{4}$ = $7^{6}$ : $7^{4}$ = $7^{6-4}$ = $7^{2}$

Bài 5:

a) 20 + 45 : 3² = 20 + 45 : 9 = 20 + 5 = 25

b) 2³ . 123 - 2³ . 23

= 2³ . (123 - 23)

= 8 . 100

= 800

c) $5^{7}$ : $5^{3}$ + 12 . 4 . $1^{0}$

= $5^{7-3}$ + 48 . 1

= $5^{4}$ + 48

= 625 + 48

=  673

Chúc học tốt!!!