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!!!
