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a ) 213. 45 . 82
= 213. ( 22 )5 . ( 23 )2
= 213. 210 . 26
= 229
b ) 369 : 189
= ( 36 : 18 )9
= 29
c ) 1006 . 10004 . 100003
= ( 102 )6 . ( 103 )4 . ( 104 )3
= 1012 . 1012 . 1012
= 1036
d ) 245 : 65 . 88
= ( 24 : 6 )5 . ( 23 )8
= 45 . 224
= ( 22 )5 . 224
= 210 . 224
= 234
a,đổi 45 thành 210
đổi 82 thành 26
ta có 210.26.213 và bằng 229
b,đổi 369 thành 1818
ta có 1818:189 và bằng 189
c,đổi 10004 thành 10040
đổi 100003 thành 100300
ta có 1006.10040.100300 bằng 100346
d,cũng làm theo cách đó và d=1310722
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) \(2^5\cdot8^4\\ =2^5\cdot\left(2^3\right)^4\\ =2^5\cdot2^{12}\\ =2^{17}\)
b) \(25^6\cdot125^3\\ =\left(5^2\right)^6\cdot\left(5^3\right)^3\\ =5^{12}\cdot5^9\\ =5^{21}\)
c) \(625^3:25^7\\ =\left(5^4\right)^3:\left(5^2\right)^7\\ =5^{12}:5^{14}\\ =5^{-2}=\frac{1}{5^2}\)
d) \(4^{10}\cdot2^{30}\\ =\left(2^2\right)^{10}\cdot2^{30}\\ =2^{20}\cdot2^{30}\\= 2^{50}\)
e) \(9^{25}\cdot27^4\cdot81^3\\ =\left(3^2\right)^{25}\cdot\left(3^3\right)^4\cdot\left(3^4\right)^3\\ =3^{50}\cdot3^{12}\cdot3^{12}\\ =3^{74}\)
a) 37:35= 32
b)46 :46= 40
C) a4 : a= a3
d) 98:32 =314
e) 85:23 = 212
f) 37:27 = 34
\(a,3^7:3^5=3^2\)
\(b,4^6:4^6=4^0\)
\(c,a^4:a=a^3\)
\(d,9^8:3^2=9^4\)
\(e,8^5:2^3=8^{-7}\)
\(f,3^7:27=3^4\)
a125^5:25^3=(5^3)^5:(5^2)^3=5^15:5^6=5^9
b27^6:9^3=(3^3)^6:(3^2)^3=3^18:3^6=3^13
c 4^20:2^15=(2^2)^20:2^15=2^40:2^15=2^25
d24^n:2^2.n=24^n:(2^2)^n=24^n:4^n=(24:4)^n=6^n
e 64^4 . 16^5:4^20=(2^6)^4 . (2^4)^5 :(2^2)^20=2^24 . 2^20:2^40=2^4
g 32^4:8^6=(2^5)^4:(2^3)^6=2^20:2^18=2^2
a, \(125^5:25^3=\left(5^3\right)^5:\left(5^2\right)^3=5^{15}:5^6=5^9\)
b, \(27^6:9^3=\left(3^3\right)^6:\left(3^2\right)^3=3^{18}:3^6=3^{12}\)
c, \(4^{20}:2^{15}=\left(2^2\right)^{20}:2^{15}=2^{40}:2^{15}=2^{25}\)
d, \(24^n:2^{2.n}=2^n.12^n:2^n.2^n=12^n:2^n=2^n.6^n:2^n=6^n\)
e, \(64^4.16^5:4^{20}=4^{12}.4^{10}:4^{20}=4^{12+10-20}=4^2\)
g, \(32^4:8^6=8^4.4^4:8^4.8^2=4^4:4^2.2^2=4^2.2^2=2^4.2^2=2^6\)
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 )
c)
Có Q = P.(x+1) = \(\frac{-3.\left(x+1\right)}{\sqrt{x}-2}\)
\(\Leftrightarrow-Q=\frac{3x+3}{\sqrt{x}-2}=\frac{3x-6\sqrt{x}+6\sqrt{x}+3}{\sqrt{x}-2}=\frac{3\sqrt{x}\left(\sqrt{x}-2\right)+6\left(\sqrt{x}-2\right)+15}{\sqrt{x}-2}\)
\(\Leftrightarrow-Q=3\sqrt{x}+6+\frac{15}{\sqrt{x}-2}\)
\(\Leftrightarrow-Q=3\left(\sqrt{x}-2\right)+\frac{15}{\sqrt{x}-2}+12\)
\(\Leftrightarrow-Q\ge2\sqrt{3\left(\sqrt{x}-2\right).\frac{15}{\sqrt{x}-2}}+12=2\sqrt{45}+12\)
\(\Leftrightarrow-Q\ge6\sqrt{5}+12\)
\(\Leftrightarrow Q\le-6\sqrt{5}-12\)
Dấu " = " Xảy ra khi :
\(3.\left(\sqrt{x}-2\right)=\frac{15}{\sqrt{x}-2}\Leftrightarrow\left(\sqrt{x}-2\right)^2=5\)
\(\Leftrightarrow\orbr{\begin{cases}\sqrt{x}-2=\sqrt{5}\\\sqrt{x}-2=-\sqrt{5}\end{cases}\Leftrightarrow\orbr{\begin{cases}\sqrt{x}=2+\sqrt{5}\Leftrightarrow x=9+4\sqrt{5}\\\sqrt{x}=2-\sqrt{5}\left(Sai\right)\end{cases}}}\)
Vậy Max Q = \(-6\sqrt{5}-12\)khi x = \(9+4\sqrt{5}\)
a ) 9^7 . 9^8 = 97+8 =915
b ) 8^6 : 8^4 = 86-4 = 82
c ) 5^3 . 8^3 = ( 5.8 )3 = 40^3
d ) 24^5 : 6^5 = ( 24:6 )5 = 4^5