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a)7.2x=56⇔2x=8⇔2x=23⇔x=3
b)(2x+1)3=9.81⇔(2x+1)3=93⇔2x+1=9⇔2x=8⇔x=4
c)x3=82⇔x3=26⇔x=22⇔x=4
d)4.2x-3=1⇔4.2x=4⇔2x=1⇔2x=20⇔x=0
e)2.3x=162⇔3x=81⇔3x=34⇔x=4
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`2^(x+2) . 3^(x+1) . 5^x = 10800`
`=> 2^x. 2^2. 3^x. 3. 5^x=10800`
`=> (2.3.5)^x. (4.3)=10800`
`=> 30^x. 12=10800`
`=> 30^x=10800:12`
`=> 30^x=900`
`=> 30^x=30^2`
`=> x=2`
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a: =>3[(2x-1)^2-4]=49*125:175+196=231
=>(2x-1)^2-4=77
=>(2x-1)^2=81
=>2x-1=9 hoặc 2x-1=-9
=>x=5 hoặc x=-4
b: \(\Leftrightarrow2\cdot3^x\cdot3-4^3=7^2\cdot\left(27-25\right)\)
=>\(6\cdot3^x=49\cdot2+64=162\)
=>3^x=27
=>x=3
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Lời giải:
a.
$3[(2x-1)^2-4]-14^2=7^2.5^3:175=35$
$3[(2x-1)^2-4]=35+14^2=231$
$(2x-1)^2-4=231:3=77$
$(2x-1)^2=77+4=81=9^2=(-9)^2$
$\Rightarrow 2x-1=9$ hoặc $2x-1=-9$
$\Rightarrow x=5$ hoặc $x=-4$
b.
$2.3^{x+1}-4^{10}:4^7=(7^5:7^3).(3^3-5^2)=7^2.2=98$
$2.3^{x+1}-4^3=98$
$2.3^{x+1}=98+4^3=162$
$3^{x+1}=162:2=81=3^4$
$\Rightarrow x+1=4$
$\Rightarrow x=3$
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\(\Rightarrow6x=5312\)
\(\Rightarrow x=5312:6\)
\(\Rightarrow x=885,3333333\)
tíc nha
\(2.3x=10.312+8.274\)
\(=2.3x=3120+2192\)
\(2.3x=5312\)
\(3x=5312:2\)
\(3x=2656\)
\(x=2656:3\)
\(x=\frac{2556}{3}\)
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\(3^x+2.3^{x-2}=297\)
\(\Rightarrow3^x\left(1+2.3^{-2}\right)=297\)
\(\Rightarrow3^x\left(1+2.\dfrac{1}{3^2}\right)=297\)
\(\Rightarrow3^x\left(1+\dfrac{2}{9}\right)=297\)
\(\Rightarrow3^x\left(\dfrac{9}{9}+\dfrac{2}{9}\right)=297\)
\(\Rightarrow3^x.\dfrac{11}{9}=297\)
\(\Rightarrow3^x=297:\dfrac{11}{9}=297.\dfrac{9}{11}=243\)
\(\Rightarrow3^x=3^5\)
\(\Rightarrow x=5\) (thỏa mãn)
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a) \(\frac{-1}{2}.3x+\frac{3}{4}=-2,25\)
\(\frac{-1}{2}.3x+\frac{3}{4}=\frac{9}{4}\)
\(\frac{-1}{2}.3x=\frac{9}{4}-\frac{3}{4}\)
\(\frac{-1}{2}.3x=\frac{6}{4}=\frac{3}{2}\)
\(3x=\frac{3}{2}:\frac{-1}{2}\)
\(3x=-3\)
\(x=\left(-3\right):3\)
\(x=-1\)
b) \(13-3\left|x-2\right|=10\)
\(3\left|x-2\right|=13-10\)
\(3\left|x-2\right|=3\)
\(\left|x-2\right|=3:3\)
\(\left|x-2\right|=1\)
\(\Rightarrow\hept{\begin{cases}\left|x-2\right|=1\\\left|x-2\right|=-1\end{cases}\Rightarrow\hept{\begin{cases}x=3\\x=1\end{cases}}}\)
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a, ( 19x + 2.52 ) : 14 = ( 13 - 8 )2 - 42
( 19x + 2.52 ) : 14 = ( 13 - 8 )2 - 16
( 19x + 2.52 ) : 14 = 52 - 16
( 19x + 2.52 ) : 14 = 25 - 16
( 19x + 2.52 ) : 14 = 9
( 19x + 2.25 ) : 14 = 9
( 19x + 2.25 ) = 9 . 14
( 19x + 2.25 ) = 126
( 19x + 50 ) = 126
19x = 126 - 50
19x = 76
x = 76 : 19
x = 4
Vậy x = 4
b, 2 . 3x = 10 . 312 + 8 . 274
2 . 3x = 10 . 274 + 8 . 274
2 . 3x = 274 . ( 10+8 )
2 . 3x = 274 . 18
2 . 3x = 9565938
3x = 9565938 : 2
3x = 4782969
3x = 314
=> x = 14
Vậy x = 14
Đây nha bạn!!!
Chúc bạn học tốt!!!
a, ( 19x + 2.52 ) : 14 = ( 13 - 8 )2 - 42
( 19x + 2.52 ) : 14 = ( 13 - 8 )2 - 16
( 19x + 2.52 ) : 14 = 52 - 16
( 19x + 2.52 ) : 14 = 25 - 16
( 19x + 2.52 ) : 14 = 9
( 19x + 2.25 ) : 14 = 9
( 19x + 2.25 ) = 9 . 14
( 19x + 2.25 ) = 126
( 19x + 50 ) = 126
19x = 126 - 50
19x = 76
x = 76 : 19
x = 4
Vậy x = 4
b, 2 . 3x = 10 . 312 + 8 . 274
2 . 3x = 10 . 274 + 8 . 274
2 . 3x = 274 . ( 10+8 )
2 . 3x = 274 . 18
2 . 3x = 9565938
3x = 9565938 : 2
3x = 4782969
3x = 314
=> x = 14
Vậy x = 14