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a) \(\left[\frac{1}{3}\right]^{50}.\left(-9\right)^{25}-\frac{2}{3}:4\)
\(\Rightarrow\frac{1}{3^{50}}.\left(-9\right)^{25}-\frac{2}{3}.\frac{1}{4}\)
\(\Rightarrow\frac{\left(-9\right)}{9^{25}}-\frac{1}{6}\)
\(\Rightarrow1-\frac{1}{6}\)
\(\Rightarrow\frac{6}{6}-\frac{1}{6}=\frac{5}{6}\)
Vậy = 5/6
\(a,10^8.2^8=\left(10.2\right)^8=20^8\)
\(b,10^8:2^8=\left(10:2\right)^8=5^8\)
\(c,25^4.2^8=25^4.\left(2^2\right)^4=25^4.4^4=\left(25.4\right)^4=100^4\)
\(d,15^8.9^4=15^8.\left(3^2\right)^4=15^8.3^8=\left(15.3\right)^8=45^8\)
\(e,27^2.25^3=\left(3^3\right)^2.\left(5^2\right)^3=3^6.5^6=\left(3.5\right)^6=15^6\)
a, 108 . 28
= ( 10 . 2 ) 8
= 208
b, 108 : 28
= ( 10 : 2 )8
= 58
c, 254 . 28
= ( 52 )4 . 28
= 58 . 28
= ( 5 . 2 ) 8
= 108
d, 158 . 94
= 158 . ( 32 )4
= 158 . 38
= ( 15 . 3 ) 8
= 458
e, 272 . 253
= ( 33 )2 . ( 52 ) 3
= 36 . 56
= ( 3 . 5 ) 6
= 15 6
bài 2
làm câu B;C nha
B)
\(27^3=\left(3^3\right)^3=3^9\)
\(9^5=\left(3^2\right)^5=3^{10}\)
vì \(10>9\)
\(=>9^5>27^3\)
C)
\(\left(\frac{1}{8}\right)^6=\left(\frac{1}{2^3}\right)^6=\frac{1^6}{2^{18}}=\frac{1}{2^{18}}\)
\(\left(\frac{1}{32}\right)^4=\left(\frac{1}{2^5}\right)^4=\frac{1^4}{2^{20}}=\frac{1}{2^{20}}\)
vì \(2^{18}< 2^{20}\)
\(=>\frac{1}{2^{18}}>\frac{1}{2^{20}}\)
\(=>\left(\frac{1}{8}\right)^6>\left(\frac{1}{32}\right)^4\)
\(\text{A.}\frac{32^3.9^5}{8^3.6^6}=\frac{\left(2^5\right)^3.\left(3^2\right)^5}{\left(2^3\right)^3.\left(2.3\right)^6}=\frac{2^{15}.3^{10}}{2^9.2^6.3^6}=\frac{3^{10}}{3^6}=3^4=81\)
\(\text{B.}\frac{\left(5^5-5^4\right)^3}{50^6}=\frac{2500^3}{50^6}=\frac{\left(50^2\right)^3}{50^6}=\frac{50^6}{50^6}=1\)
Bài 2:
\(\text{A.Ta có:}\)
\(5^6=\left(5^3\right)^2=125^2\)
\(\left(-2\right)^{14}=2^{14}=\left(2^7\right)^2=128^2\)
Vì \(125< 128\)
\(\Rightarrow125^2< 128^2\)
\(\Rightarrow5^6< \left(-2\right)^{14}\)
\(\text{B.Ta có:}\)
\(9^5=\left(3^2\right)^5=3^{10}\)
\(27^3=\left(3^3\right)^3=3^9\)
Vì \(9< 10\)
\(\Rightarrow3^9< 3^{10}\)
\(\Rightarrow27^3< 9^5\)
\(\text{C.Ta có:}\)
\(\left(\frac{1}{8}\right)^6=\left[\left(\frac{1}{2}\right)^3\right]^6=\left(\frac{1}{2}\right)^{18}\)
\(\left(\frac{1}{32}\right)^4=\left[\left(\frac{1}{2}\right)^5\right]^4=\left(\frac{1}{2}\right)^{20}\)
Vì \(18< 20\)
\(\Rightarrow\left(\frac{1}{2}\right)^{18}< \left(\frac{1}{2}\right)^{20}\)
\(\Rightarrow\left(\frac{1}{8}\right)^6< \left(\frac{1}{32}\right)^4\)
\(\left(\dfrac{1}{3}\right)^{50}.\left(-9\right)^{25}-\dfrac{2}{3}:4\)
\(=\left(\dfrac{1}{3}\right)^{50}.\left[\left(-3\right)^2\right]^{25}-\dfrac{2}{3}.\dfrac{1}{4}\)
\(=\left(\dfrac{1}{3}\right)^{50}.\left(-3\right)^{50}-\dfrac{2}{12}\)
\(=\left[\dfrac{1}{3}.\left(-3\right)\right]^{50}-\dfrac{1}{6}\)
\(=\left(-1\right)^{50}-\dfrac{1}{6}\)
\(=1-\dfrac{1}{6}\)
\(=\dfrac{6}{6}-\dfrac{1}{6}\)
\(=\dfrac{5}{6}\)
\(\left(\dfrac{1}{3}\right)^{50}\cdot\left(-9\right)^{25}-\dfrac{2}{3}:4=\)
=\(\dfrac{1}{3^{50}}\cdot\left(-9\right)^{25}-\dfrac{2}{3}\cdot\dfrac{1}{4}\)
=\(\dfrac{\left(-9\right)^{25}}{9^{25}}-\dfrac{1}{6}\)
=\(-1-\dfrac{1}{6}\)
=\(-\dfrac{6}{6}-\dfrac{1}{6}\)
=\(-\dfrac{7}{6}\)