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NV
0
HH
25 tháng 7 2015
\(\left(0,125\right)^3.512=\frac{1}{512}.512\)
\(=1\)
\(\left(0,25\right)^4.1024=\frac{1}{256}.1024\)
\(=\frac{1.4}{1.1}\)
\(=4\)
ND
Nguyễn Đức Trí
VIP
27 tháng 7 2023
Bài 6 :
a) \(\dfrac{625}{5^n}=5\Rightarrow\dfrac{5^4}{5^n}=5\Rightarrow5^{4-n}=5^1\Rightarrow4-n=1\Rightarrow n=3\)
b) \(\dfrac{\left(-3\right)^n}{27}=-9\Rightarrow\dfrac{\left(-3\right)^n}{\left(-3\right)^3}=\left(-3\right)^2\Rightarrow\left(-3\right)^{n-3}=\left(-3\right)^2\Rightarrow n-3=2\Rightarrow n=5\)
c) \(3^n.2^n=36\Rightarrow\left(2.3\right)^n=6^2\Rightarrow\left(6\right)^n=6^2\Rightarrow n=6\)
d) \(25^{2n}:5^n=125^2\Rightarrow\left(5^2\right)^{2n}:5^n=\left(5^3\right)^2\Rightarrow5^{4n}:5^n=5^6\Rightarrow\Rightarrow5^{3n}=5^6\Rightarrow3n=6\Rightarrow n=3\)
ND
Nguyễn Đức Trí
VIP
27 tháng 7 2023
Bài 7 :
a) \(3^x+3^{x+2}=9^{17}+27^{12}\)
\(\Rightarrow3^x\left(1+3^2\right)=\left(3^2\right)^{17}+\left(3^3\right)^{12}\)
\(\Rightarrow10.3^x=3^{34}+3^{36}\)
\(\Rightarrow10.3^x=3^{34}\left(1+3^2\right)=10.3^{34}\)
\(\Rightarrow3^x=3^{34}\Rightarrow x=34\)
b) \(5^{x+1}-5^x=100.25^{29}\Rightarrow5^x\left(5-1\right)=4.5^2.\left(5^2\right)^{29}\)
\(\Rightarrow4.5^x=4.25^{2.29+2}=4.5^{60}\)
\(\Rightarrow5^x=5^{60}\Rightarrow x=60\)
c) Bài C bạn xem lại đề
d) \(\dfrac{3}{2.4^x}+\dfrac{5}{3.4^{x+2}}=\dfrac{3}{2.4^8}+\dfrac{5}{3.4^{10}}\)
\(\Rightarrow\dfrac{3}{2.4^x}-\dfrac{3}{2.4^8}+\dfrac{5}{3.4^{x+2}}-\dfrac{5}{3.4^{10}}=0\)
\(\Rightarrow\dfrac{3}{2}\left(\dfrac{1}{4^x}-\dfrac{1}{4^8}\right)+\dfrac{5}{3.4^2}\left(\dfrac{1}{4^x}-\dfrac{1}{4^8}\right)=0\)
\(\Rightarrow\left(\dfrac{1}{4^x}-\dfrac{1}{4^8}\right)\left(\dfrac{3}{2}+\dfrac{5}{3.4^2}\right)=0\)
\(\Rightarrow\dfrac{1}{4^x}-\dfrac{1}{4^8}=0\)
\(\Rightarrow\dfrac{4^8-4^x}{4^{x+8}}=0\Rightarrow4^8-4^x=0\left(4^{x+8}>0\right)\Rightarrow4^x=4^8\Rightarrow x=8\)
NK
0
T
15 tháng 10 2023
\(\dfrac{5^{20}-5^{15}}{5^{16}+5^{18}}\)
\(=\dfrac{5^{15}\cdot\left(5^5-1\right)}{5^{16}\cdot\left(1+5^2\right)}\)
\(=\dfrac{3125-1}{5\cdot\left(1+25\right)}\)
\(=\dfrac{3124}{5\cdot26}\)
\(=\dfrac{1562}{65}\)
15 tháng 10 2023
\(\dfrac{5^{20}-5^{15}}{5^{16}+5^{18}}\\ =\dfrac{5^{15}\left(5^5-1\right)}{5^{16}\left(1+5^2\right)}\\ =\dfrac{5^5-1}{5\left(1+25\right)}\\ =\dfrac{3125-1}{5\cdot26}\\ =\dfrac{3124}{130}\\ =\dfrac{1562}{65}\)
30 tháng 8 2023
\(\left(\dfrac{5}{2}\right)^{18}:\left(1+\dfrac{3}{2}\right)^{17}\)
\(=\left(\dfrac{5}{2}\right)^{18}:\left(\dfrac{5}{2}\right)^{17}\)
\(=\dfrac{5}{2}\)
H9
HT.Phong (9A5)
CTVHS
30 tháng 8 2023
\(\left(\dfrac{5}{2}\right)^{18}:\left(1+\dfrac{3}{2}\right)^{17}\)
\(=\left(\dfrac{5}{2}\right)^{18}:\left(\dfrac{2}{2}+\dfrac{1}{2}\right)^{17}\)
\(=\left(\dfrac{5}{2}\right)^{18}:\left(\dfrac{5}{2}\right)^{17}\)
\(=\left(\dfrac{5}{2}\right)^{18-17}\)
\(=\dfrac{5}{2}\)
(-3)18 = 318 = 310 . 38
1024 . 365 = 210.(22.32)5 = 210.210.310 = 310. 220 = 310.(22)10=310.410
Vì 38 < 48 < 410 vậy 310 . 38 < 310 . 410 => (-3)18 < 1024.(36)5