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a ) 5^n = 125
5^n = 5^3
n = 3
b ) 3^4 . 3^n = 3^7
3^(4 + n ) =3^7
4 + n = 7
n = 7 - 4
n = 3
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Bài 3 :
a) 4.(x-5) - 2 3=24.3
4x-20-8=48
4x=76
x=19
b) 4.x3+15=271
4.x3=256
x3=64
=> x=4
c) ( 2x-3)2= 169
=> 2x-3= 13
2x=16
x=8
Chúc bạn học tốt !
4*(x-5) - 2^3 = 2^4*3
4*(x-5) - 8 = 16*3
4*(x-5) - 8 = 48
4*(x-5) = 48 + 8
4*(x-5) = 56
x- 5 = 56 : 4
x - 5 = 14
x = 14 + 5
x = 19
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a)\(\left(\frac{1}{2}-\frac{1}{3}\right).6^x+6^{x+2}=6^{15}+6^{18}\)
\(\frac{1}{6}.6^x+6^{x+2}=6^{15}\left(1+6^3\right)\)
\(\frac{1}{6}.6^x\left(1+6^3\right)=6^{15}.217\)
\(6^{x-1}.217=6^{15}.217\)
\(6^{x-1}=6^{15}\)
\(x-1=15\)
\(x=16\)
b) \(\left(\frac{1}{2}-\frac{1}{6}\right).3^{x+4}-4.3^x=3^{16}-4.3^{13}\)
\(\frac{1}{3}.3^x.4\left(3^4-1\right)=3^{13}.4\left(3^3-1\right)\)
\(3^x.4.\left(3^3-1\right)=3^{13}.4.\left(3^3-1\right)\)
\(3^x=3^{13}\)
\(x=13\)
\(\left(\frac{1}{2}-\frac{1}{6}\right).\left(3^x.3^4\right)-4.3^x=3^{16}-4.3^{13}\)
=> \(\frac{1}{3}.3^x.3^4-4.3^x=3^{16}-4.3^{13}\)
=> \(3^x.3^4-4.3^x=\left(3^{16}-4.3^{13}\right):\frac{1}{3}\)
=> \(3^x.3^4-4.3^x=-386339074,3\)
=> \(3^x.\left(3^4-4\right)=-386339074,3\)
=> \(3^x.77=-386339074,3\)
=> \(3^x=-386339074,3:77\)
=> \(3^x=-5017390,575\)
=> x = ... chắc tự ngồi tính đc
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a) 1440: [41-{2x-5}]=16.3
41-(2x-5)=1440-48
41-(2x-5)=1392
2x-5=41-1392
2x-5=-1351
2x=-1351+5
2x=-1346
x=(-1346):2
x=-673
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 5.22 + (x + 3) = 52
5.4 + (x + 3) = 25
5.4 + x + 3 = 25
20 + x + 3 = 25
x + 23 = 25
x = 25 - 23
b) 23 + (x - 32) = 53 - 43
8 + (x - 9) = 125 - 64
8 + x - 9 = 61
x - 1 = 61
x = 61 + 1
x = 62
c) 4(x - 5) - 23 = 24.3
4(x - 5) - 8 = 16.3
4(x - 5) - 8 = 48
4(x - 5) = 48 + 8
4(x - 5) = 56
x - 5 = 56 : 4
x - 5 = 14
x = 14 + 5
x = 19
![](https://rs.olm.vn/images/avt/0.png?1311)
\(3^{x+1}+3^{x+2}+3^{x+3}-4.3^x=315\)
\(\Leftrightarrow3^x.3+3^x.3^2+3^x.3^3-4.3^x=315\)
\(\Leftrightarrow3^x.3+3^x.9+3^x.27-4.3^x=315\)
\(\Leftrightarrow3^x.\left(3+9+27-4\right)=315\)
\(\Leftrightarrow3^x.35=315\)\(\Leftrightarrow3^x=9\)
\(\Leftrightarrow3^x=3^2\)\(\Leftrightarrow x=2\)
Vậy \(x=2\)
Bài làm :
Ta có :
\(3^{x+1}+3^{x+2}+3^{x+3}-4.3^x=315\)
\(\Leftrightarrow3^x.3+3^x.3^2+3^x.3^3-4.3^x=315\)
\(\Leftrightarrow3^x.3+3^x.9+3^x.27-4.3^x=315\)
\(\Leftrightarrow3^x.\left(3+9+27-4\right)=315\)
\(\Leftrightarrow3^x.35=315\)
\(\Leftrightarrow3^x=9\)
\(\Leftrightarrow3^x=3^2\)
\(\Leftrightarrow x=2\)
Vậy x=2
Ta có: 4.(x-5)-2^3=2^4.3
4.(x-5)-8=48
4.(x-5)=56
x-5=14
x=19
Vậy x=19
nhớ k cho mk nhá, điểm mk đang âm, cảm ơn nhiều!!!