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a) Ta có : 5x = 125
=> 5x = 53
=> x = 3
b) Ta có : 32x = 81
=> 32x = 34
=> 2x = 4
=> x = 4 : 2 = 2
c) Ta có : 52x + 3 - 2 . 52 = 52 . 3
=> 52x + 3 = 52 . 3 + 2 . 52
=> 52x + 3 = 52 . (3 + 2)
=> 52x + 3 = 52 . 5 = 53
=> 2x + 3 = 3
=> 2x = 3 - 3 = 0
=> x = 0 : 2 = 0
a)5x=125<=>5x=53=>x=3
b)32x=81<=>32x=34=>2x=4=>x=2
c)52x+3-50=75
52x+3=75+50
52x+3=125
<=>52x+3=53
=>2x+3=3
=>2x=0
=>x=0
a) 52x+1=125
=>52x+1= 53
=>2x+1=3
=>2x = 2
=>x =1
c)73<x <=93
=>343<x<=729
=> x = { 344;345;...;729}
d) (2x+3)4=81
=>(2x+3)4=34
=>2x+3 =3
=>2x =0
=> x = 0
nhớ tk nha
a)52x+1=125
52x+1=53
⏩ 2x+1=3
2x=4
x=4:2
x=2
b) (2x)2(2x) 3 =25.25
(2x) 2 (2x) 3 =210
(2x) 5=1024
(2x) 5 =45
2x=4
x=4 :2=2
d)(2x +3)4=81
(2x +3)4=34
2x+3=3
2x=0
x=0
Câu c bạn tự giải nhé
Nhớ tk giùm mình đấy
a,Vì |a|<5
=>|a|\(\in\){0,1,2,3,4}
=>a\(\in\){-4,-3,-2,-1,0,1,2,3,4}
=>-5<a<5\(\left(đpcm\right)\)
b,5x=125
=>5x=53
=>x=3
c,32x=81
=>(32)x=81
=>9x=81
=>9x=92
=>x=2
d,52x-3-2.52=52.3
=>52x:53-2.25=25.3
=>52x:53-50=75
=>52x:53=75+50
=>52x:53=125
=>52x=125.53
=>52x=53.53
=>52x=56
=>2x=6
=>x=3
\(a,4^{2x-6}=1\)\(\Leftrightarrow2x-6=0\Leftrightarrow2x=6\Rightarrow x=3\)
\(b,2^{2x-1}=16\Rightarrow2^{2x-1}=2^4\)
\(\Rightarrow2x-1=4\Rightarrow2x=5\Rightarrow x=\frac{5}{2}\)
\(c,5< 5^x< 125\Rightarrow5^1< 5^x< 5^3\)\(\Rightarrow1< x< 3\)
\(d,5^{x+1}=125\Rightarrow5^{x+1}=5^3\Rightarrow x+1=3\Rightarrow x=2\)
\(a,4^{2x-6}=1\)
\(4^{2x-6}=4^0\)
\(\Rightarrow2x-6=0\)
\(\Rightarrow2x=6\Leftrightarrow x=3\)
\(b,2^{x-1}=16\)
\(2^{x-1}=2^4\)
\(\Rightarrow x-1=4\)
\(\Rightarrow x=5\)
a) 5^x=125
=> 5^x=5^2
=>x=2
b) 3^2*x=81
=>3^2*x=9^2
=>3^2*x=(3^2)^2
=>x=2
câu c chưa hiểu chỗ 5^2x3 hay 5^2*3 vậy ?
a) \(5^x=125\)
\(5^x=5^3\)
\(\Rightarrow x=3\)
b)\(3^{2x}=81\)
\(3^{2x}=3^4\)
\(\Rightarrow2x=4\)
\(x=4:2\)
\(x=2\)
c)\(5^{2x-3}-2.5^2=5^2.3\)
\(5^{2x-3}=5^2.3+5^2.2\)
\(5^{2x-3}=5^2.\left(3+2\right)\)
\(5^{2x-3}=5^3\)
\(\Rightarrow2x-3=3\)
\(2x=3+3\)
\(2x=6\)
\(x=6:2\)
\(x=3\)
Tìm x , biết:
a, ( 2x + 1)2 = 93
b, ( 2x + 1)3 = 1252
c, 252< 5x+3 < 254
d, x15= x
e, ( x - 5)4 = ( x-5)6
A) \(\left(2x+1\right)^2=9^3\)
\(\Rightarrow\left(2x+1\right)^2=9^2\times9\)
\(\Rightarrow2x+1=81\)
\(\Rightarrow2x=81-1\)
\(\Rightarrow2x=80\)
\(\Leftrightarrow x=40\)
B) \(\left(2x+1\right)^3=125^2\)
\(\Rightarrow\left(2x+1\right)^3=5^3\)
\(\Rightarrow2x+1=5\)
\(\Rightarrow2x=5-1\)
\(\Leftrightarrow x=2\)
C) \(25^2< 5^{x+3}< 25^4\)
\(\Leftrightarrow5^4< 5^{x+3}< 5^6\)
\(\Leftrightarrow4< x+3< 6\)
\(\Rightarrow x+3=5\)
\(\Rightarrow x=2\)
D) \(x^{15}=x\)
Nếu \(x>1\)thì \(x^{15}>x\)
Vậy \(x=1\)
E) \(\left(x-5\right)^4=\left(x-5\right)^6\)
\(\Rightarrow\left(x-5\right)^4-\left(x-5\right)^6=0\)
\(\Rightarrow\left(x-5\right)\times\left(1^4-1^6\right)=0\)
\(\Rightarrow x-5=0\)
\(\Leftrightarrow x=5\)
KÍCH MK NHA BẠN
a) 5x = 125
\(\Rightarrow\)5x = 53
\(\Rightarrow\)x = 3
b, 32x = 81
\(\Rightarrow\)32x = 34
\(\Rightarrow\)2x = 4
\(\Rightarrow\) x = 4 : 2
\(\Rightarrow\) x = 2
c, 52x-3 - 2 . 52 = 52 . 3
52x-3 - 2 . 25 = 25 . 3
52x-3 - 50 = 75
52x-3 = 75 + 50
52x-3 = 125
52x-3 = 53
2x - 3 = 3
2x = 3 + 3
2x = 6
x = 6 : 2
x = 3
a, 5x = 125 suy ra 5x = 53 suy ra x = 3
b, 32x = 81 suy ra 32x = 34 suy ra x = 2
c, 52x - 3 - 2.52 = 52 . 3
suy ra 52x : 53 = 52 .3 + 2. 52
suy ra 52x : 53 = 52 . 5
suy ra 52x = 53 . 52 . 53
52x = 56 suy ra 2x = 6 suy ra x = 3
a)5x=125=53
=>x=3
b)32x=81=34
=>2x=4
x=4/2
x=2
c)52x-3-2*52=52*3
52x-3=52*3+2*52=52(3+2)=52*5
52x-3=53
=>2x-3=3
2x=3+3
2x=6
x=6/2
x=3
lần sau nếu ghi dẫu mũ như vậy thì bạn nhớ ngoặc vào
a)\(5^x=125\)
\(\Rightarrow5^x=5^3\Rightarrow x=3\)
b)\(3^{2x}=81\)
\(\Rightarrow3^{2x}=3^4\)
\(\Rightarrow2x=4\Rightarrow x=2\)
c)\(5^{2x-3}-2\cdot5^2=5^2\cdot3\)
\(\Rightarrow5^{2x-3}-2\cdot25=25\cdot3\)
\(\Rightarrow5^{2x-3}-50=75\)
\(\Rightarrow5^{2x-3}=125\)
\(\Rightarrow5^{2x-3}=5^3\)
\(\Rightarrow2x-3=3\)
\(\Rightarrow2x=6\Rightarrow x=3\)
|x|<5 =>x\(\in\)(-5;5)