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a)
1/9 . 34.3n=37
=>3-2.34.3n=37
=>3-2+4+n=37
=>-2+4+n=7
=>n=7-(-2)-4
=>n=5
#)Giải :
\(\frac{1}{9}.3^4.3^n=3^7\)
\(\frac{1}{9}.81.3^n=3^7\)
\(9.3^n=3^7\)
\(3^2.3^n=3^7\)
\(\Rightarrow2+n=7\)
\(\Rightarrow n=5\)
#~Will~be~Pens~#
a Ta có
1/9.3^4.3^n=3^7
=> 1/3^2.3^4.3^n=3^7
=> 3^2.3^n=3^7
=>3^2+n=3^7
=> 2+n=7
=> n=5( tick nhé)
Trl :
32 < 2n < 128 2.16 \(\ge\)2n > 4 125 < 5n < 625
25 < 2n < 27 25 \(\ge\)2n > 22 53 < 5n < 54
5 < n < 7 5 \(\ge\)n > 2 => 3 < n < 4
=> n = 6 \(\Rightarrow n\in\left\{5;4;3;2\right\}\) => \(n\in\varnothing\)
Hok tốt
\(a,2^{n+1}=16\)
\(\Leftrightarrow2^{n+1}=2^4\)
\(\Leftrightarrow n+1=4\)
\(\Leftrightarrow n=3\)
\(b,2.2^n=32\)
\(\Leftrightarrow2^{n+1}=2^5\)
\(\Leftrightarrow n+1=5\)
\(\Leftrightarrow x=4\)
\(c,15< 2^n< 70\)
\(\Rightarrow x=\left\{4;5;6\right\}\)
a/ \(2^{n+1}=16\)
\(\Leftrightarrow2^{n+1}=2^4\)
\(\Leftrightarrow n+1=4\)
\(\Leftrightarrow x=3\)
Vậy ..........
b/ \(2.2^n=32\)
\(\Leftrightarrow2^n=16\)
\(\Leftrightarrow2^n=2^4\)
\(\Leftrightarrow n=4\)
a)5^36=(5^3)^12=125^12
11^24=(11^2)^12=121^12
Vi 125^12>121^12=>5^36>11^24
a)16x<1284
=>(24)x<(27)4
=>24x<228
<=>4x<28
<=>x<7
=>x={0;1;2;3;4;5;6}
b)5x.5x+1.5x+2<100...0:218
<=>53x+3<1018:218=(10:2)18=518
<=>3x+3<18
<=>3x<15
<=>x<5
<=>x={0;1;2;3;4}
a) 16x < 1284
(24)x<(27)4
24x<228
=>4x<28
=>x<28:4
=>x<7
mà x\(\in\)N nên
0\(\le\)x<7
b) 5x . 5x + 1 . 5x + 2 < 10.....0 : 218
5x+x+1+x+2<1018:218
53x+3<(10:2)18
53x+3<518
=>3x+3<18
=>3x<18-3
=>3x<15
=>x<15:3
=>x<5 mà x\(\in\)N nên
0\(\le\)x<5
a)16^n<128^4
=>(2^4)^n<(2^7)^4
=>2^4n<2^28
=>4n<28
=>n<28:4
=>n<7
=>n E {0;1;2;3;4;5;6}
b)32<2^n<128
=>2^5<2^n<2^7
=>5<n<7
=>n=6
c)2.16>2^n>4
=>2.2^4>2^n>2
=>2<2^n<2^5
=>1<n<5
=>n E {2;3;4}
tick nhé