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\(a,213=200+10+3\)\(=\left(2x10^2\right)\)\(+10^1\)\(+\left(3x10^0\right)\)
\(b,421=400+20+1\)\(=\left(4x10^2\right)\)\(+\left(2x10^1\right)\)\(+10^0\)
\(c,1256=1000+200+50+6\)\(=10^3\)\(+\left(2x10^2\right)\)\(+\left(5x10^1\right)\)\(+\left(6x10^0\right)\)
\(d,2006=2000+6\)\(=\left(2x10^3\right)\)\(+\left(6x10^0\right)\)
\(e,abc=100a+10b+c=10^2\)\(a+10^1\)\(b+\left(cx10^0\right)\)
\(g,abcde=10000a+1000b+100c+10d+e\)\(=10^4\)\(a+10^3\)\(b+10^2\)\(c+10^1\)\(d+e\)
Bài 9: Viết các số sau dưới dạng tổn các lũy thừa của 10
a) 213 = 2 . 100 + 1 . 10 + 3 . 1 = 2 . 102 + 2 . 101 + 3 . 100
b) 421 = 4 . 100 + 2 . 10 + 1 . 1 = 4 . 102 + 2 . 101 + 1 . 100
c) 1256 = 1 . 1000 + 2 . 100 + 5 . 10 + 6 . 1 = 1 . 103 + 2 . 102 + 5 . 101 + 6 . 100
d) 2006 = 2 . 1000 + 6 . 1 = 2 . 103 + 1 . 100
e) abc = a . 100 + b . 10 + c . 1 = a . 102 + b . 101 + c . 100
g) abcde = a . 10000 + b . 1000 + c . 100 + d . 10 + e . 1 = a . 104 + b . 103 + c .102 + d . 101 + e . 100
Bài 10: Viết mỗi thương sau dưới dạng 1 lũy thừa
a) 38 : 36 = 32
75 : 72 = 73
197 : 193 = 194
210 : 83 = 210 : ( 23 )3 = 210 : 29 = 21 = 2
127 : 67 = ( 12 : 6 )7 = 27
275 : 813 = ( 33 )5 : ( 34 )3 = 315 : 312 = 33
b) 106 : 10 = 105
58 : 252 = 58 : ( 52 )2 = 58 : 54 = 54
49 : 642 = 49 : ( 43 )2 = 49 : 46 = 43
225 : 324 = 225 : ( 25 )4 = 225 : 220 = 5
183 : 93 = ( 18 : 9 )3 = 23
1253 : 254 = ( 53 )3 : ( 52 )4 = 59 : 58 = 5
a) $3^8:3^6=3^{8-6}=3^2$
$19^7:19^3=19^{7-3}=19^4$
$2^{10}:8^3=2^{10}:(2^3)^3=2^{10}:2^9=2^{10-9}=2^1$
$12^7:6^7=(12:6)^7=2^7$
$27^5:81^3=(3^3)^5:(3^4)^3=3^{15}:3^{12}=3^{15-12}=3^3$
b) $10^6:10=10^{6-1}=10^5$
$5^8:25^2=5^8:(5^2)^2=5^8:5^4=5^{8-4}=5^4$
$4^9:64^2=4^9:(4^3)^2=4^9:4^6=4^{9-6}=4^3$
$2^25:32^4=2^{25}:(2^5)^4=2^{25}:2^{20}=2^{25-20}=2^5$
$18^3:9^3=(18:9)^3=2^3$
\(\cdot3^8:3^6=3^{8-6}=3^2\)
\(\cdot19^7:19^3=19^{7-3}=19^4\)
\(\cdot2^{10}:8^3=2^{10}:\left(2^3\right)^3=2^{10}:2^9=2\)
\(\cdot12^7:6^7=\left(12:6\right)^7=2^7\)
\(\cdot27^5:81^3=\left(3^3\right)^5:\left(3^4\right)^3=3^{15}:3^{12}=3^3\)
\(\cdot10^6:10=10^{6-1}=10^5\)
\(\cdot5^8:25^2=5^8:\left(5^2\right)^2=5^8:5^4=5^4\)
\(\cdot4^9:64^2=4^9:\left(4^3\right)^2=4^9:4^6=4^3\)
\(2^{25}:32^4=2^{25}:\left(2^5\right)^4=2^{25}:2^{20}=2^5\)
\(18^3:9^3=\left(18:9\right)^3=2^3\)
a) \(4^{10}.2^{30}=\left(2^2\right)^{10}.2^{30}=2^{2.10}.2^{30}=2^{20}.2^{30}=2^{20+30}=2^{50}\)
b) \(9^{25}.27^4.81^3=\left(3^2\right)^{25}.\left(3^3\right)^4.\left(3^4\right)^3=3^{3.25}.3^{3.4}.3^{4.3}=3^{75}.3^{12}.3^{12}=3^{75+12+12}=3^{99}\)
c) \(25^{50}.125^5=\left(5^2\right)^{50}.\left(5^3\right)^5=5^{2.50}.5^{3.5}=5^{100}.5^{15}=5^{100+15}=5^{115}\)
d) \(64^3.4^8.16^4=\left(4^3\right)^3.4^8.\left(4^2\right)^4=4^{3.3}.4^8.4^{2.4}=4^9.4^8.4^8=4^{9+8+8}=4^{25}\)
e) \(3^8:3^6=3^{8-6}=3^2\)
f) \(2^{10}:8^3=2^{10}:\left(2^3\right)^3=2^{10}:2^{3.3}=2^{10}:2^9=2^{10-9}=2\)
g) \(12^7:6^7=\left(12:6\right)^7=2^7\)
h_ \(21^5:81^3\)kết quả là số dư nên không tính ( đề sai )
Bài 4: Viết các tích sau đây dưới dạng 1 lũy thừa của 1 số
A = 82.324 = ( 23 )2 . ( 25 )4 = 26 . 220 = 226
B = 273.94.243 = ( 33 )3 . ( 32 )4 . 35 = 39 . 38 . 35 = 322
C = 410.815 = ( 22 )10 . ( 23 )15 = 220 . 245 = 265
D = 415.530 = ( 22 )15 . 530 = 230 . 530 = ( 2 . 5 )30 = 1030
E = 2716 : 910 = ( 33 )16 . ( 32 )10 = 348 . 320 = 368
F = 25.84 = 25 . ( 23)4 = 25 . 212= 217
g = 256.1253 = ( 52 )6 . ( 53 )3 = 512 . 59 = 521
H = 123.33 = ( 12.3 )3 = 363
B:6 so sánh
a, \(7^{18}\) + \(7^{19}\) và \(7^{20}\)
ta có : \(7^{18}\) + \(7^{19}\) = \(7^{37}\)
mà \(7^{37}\) > \(7^{12}\)
\(\Rightarrow\) \(7^{18}\) + \(7^{19}\) > \(7^{20}\)
a) 27^16 : 9^10
Ta có: (3.9)^16 : 9^10
= 3^16.9^16: 9^10
= 3^16. 9^6
= 3^16.(3^2)^6
=3^16.3^12
=3^28
a.\(\hept{\begin{cases}4^8.2^{20}=2^{16}.2^{20}=2^{36}\\9^{12}.27^5.81^4=3^{24}.3^{15}.3^{12}=3^{51}\\64^3.4^5.16^2=2^{18}.2^{10}.2^8=2^{36}\end{cases}}\)
b.\(\hept{\begin{cases}25^{20}.125^4=5^{40}.5^{12}=5^{52}\\x^7x^4x^3=x^{14}\\3^6.4^6=12^6\end{cases}}\)
c.\(\hept{\begin{cases}8^4.2^3.16^2=2^{12}.2^3.2^8=2^{23}\\2^3.2^2.8^3=2^3.2^2.2^9=2^{14}\end{cases}}\)
Bài 1 :
a/ \(a^3.a^9=a^{3+9}=a^{12}\)
b/\(\left(a^5\right)^7=a^{5.7}=a^{35}\)
c/ \(\left(a^6\right).4.a^{12}=a^{24}.a^{12}.4=a^{24+12}.4=a^{36}.4\)
d/ \(\left(2^3\right)^5.\left(2^3\right)^3=2^{15}.2^9=2^{15+9}=2^{24}\)
e/ \(5^6:5^3+3^3.3^2\)
\(=5^3+3^5=125+243=368\)
i/ \(4.5^2-2.3^2\)
\(=2^2.5^2-2.3^2\)
\(=2^2.25-2^2.14\)
\(=2^2.\left(25-14\right)\)
\(=2^2.11\)
\(=4.11=44\)
Bài 2 :
a, \(3^8:3^6=3^{8-6}=3^2\)
\(7^5:7^2=7^{5-2}=7^3\)
\(19^7:19^3=19^{7-3}=19^4\)
\(2^{10}.8^3=2^{10}.\left(2^3\right)^3=2^{10}.2^9=2^{19}\)
\(12^7:6^7=\left(12:6\right)^7=2^7=128\)
\(27^5:81^3=\left(3^3\right)^5:\left(3^4\right)^3=3^{15}:3^{12}=3^3=9\)