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2x + 2x+3 = 144
\(\Rightarrow\)2x + 2x . 8 = 144
\(\Rightarrow\)2x . ( 8 + 1 ) = 144
\(\Rightarrow\)2x . 9 = 144
\(\Rightarrow\)2x = 16
\(\Rightarrow\)2x = 24
\(\Rightarrow\)x = 4
( 4x - 1 ) 2 = 25 . 9
\(\Rightarrow\)(4x - 1 )2 = 52 . 32
\(\Rightarrow\)(4x - 1 ) 2 = 152
\(\Rightarrow\)4x - 1 = 15
\(\Rightarrow\)4x = 16
\(\Rightarrow\)x = 4
(4x+5) : 3 -121 : 11 = 4
=> (4x + 5) : 3 - 11 = 4
=> (4x + 5) : 3 = 15
=> 4x + 5= 45
=> 4x = 40
=> x=10
Vậy...
(2x + 1)3 = 125
=> (2x + 1)3= 53
=> 2x + 1= 5
=> 2x= 4
=> x=2
Vậy...
(4x - 1)2 = 25.9
=> (4x - 1)2= (5.3)2
=> 4x - 1= 15
=> 4x = 16
=> x = 4
Vậy...
2x + 2x+3= 144
=> 2x . (1 + 23) = 144
=> 2x . 9= 144
=> 2x = 16 = 24
=> x= 4
Vậy...
1 + 3 + 5 + ... + x = 1000 ( x lẻ)
Số số hạng của dãy số (1 + 3 + 5 + ... + x) là:
(x - 1) : 2 + 1 = (x-1)/2 + 2/2 = x - 1 + 2= (x + 1)/2 (số hạng)
=> (x+1)(x+1)/2 : 2=1000
=> (x+1)(x+1)=4000
=> (x+1)2= 4000
Ta có: 4000= 25.53
=> 4000 có số lượng ước là: (5+1).(3+1)= 24 là số chẵn
=> 4000 k phải là số chính phương
=> Không tìm được giá trị của x
Vậy...
\(a.2^x+2^{x+3}=144\)
\(2^x+2^x.2^3=144\)
\(2^x+2^x.8=144\)
\(2^x.\left(1+8\right)=144\)
\(2^x.9=144\)
\(2^x=144:9\)
\(2^x=16\)
\(2^x=2^4\)
\(\Rightarrow x=4\)
Vậy \(x=4\)
\(b.\left(4.x-1\right)^2=25.9\)
\(\left(4.x-1\right)^2=225^2\)
\(4.x-1=225\)
\(4.x=225+1\)
\(4.x=226\)
\(x=226:4\)
\(x=\frac{226}{4}=\frac{113}{2}\)
Vậy \(x=\frac{113}{2}\)
2x + 2x+3 = 144
<=> 2x + 2x.23 = 144
<=> 2x( 1 + 23 ) = 144
<=> 2x.9 = 144
<=> 2x = 16
<=> 2x = 24
<=> x = 4
( 4x - 1 )2 = 25 . 9
<=> ( 4x - 1 )2 = 52 . 32
<=> ( 4x - 1 )2 = ( 5 . 3 )2
<=> ( 4x - 1 )2 = 152 = (-15)2
<=> \(\hept{\begin{cases}4x-1=15\\4x-1=-15\end{cases}}\Leftrightarrow\hept{\begin{cases}x=4\\x=-\frac{7}{2}\end{cases}}\)
Tham khảo:Tìm x thuộc N , biết:a) 2x + 2x+3 =144b) (4x -1)2 =25 x 9 - Hoc24
bài 1
gọi số cần tìm là A
ta có : A=60. q +31
A=12.17+r (0<r <12)
ta thấy 60. q chia hết cho 12
ta có 31:12 =2 (dư 7)
=> r=7
A=12.17+7
A=204+7
A=211
bài 2
b) (4x+ 5) :3 -121 :11 =4
(4x+5):3-11 =4
(4x+5):3 =4+11
(4x+5) :3=15
4x+5 =15.3
4x+5 =45
4x =45-5
4x=40
x=40:4
x=10
\(4^{x-5}=16\)
\(4^{x-5}=4^2\)
\(x-5=2\)
\(x=2+5\)
\(x=7\)
\(45-2^{x-1}=29\)
\(2^{x-1}=16\)
\(2^{x-1}=2^4\)
\(x-1=4\)
\(x=5\)
\(\left(2+x\right)^2=144\)
\(\left(2+x\right)^2=12^2\)
\(2+x=12\)
\(x=12-2\)
\(x=10\)
\(\left(x-5\right)^2=81\)
\(\left(x-5\right)^2=9^2\)
\(x-5=9\)
\(x=14\)
\(\left(13-x\right)^4=81\)
\(\left(13-x\right)^4=3^4\)
\(13-x=3\)
\(x=13-3\)
\(x=10\)
\(...4^{x-5}=4^2\Rightarrow x-5=2\Rightarrow x=7\)
\(...2^{x-1}=45-29=16\Rightarrow2^{x-1}=2^4\Rightarrow x-1=4\Rightarrow x=5\)
\(...\Rightarrow\left(2+x\right)^2=12^2\Rightarrow\left[{}\begin{matrix}2+x=12\\2+x=-12\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=10\\x=-14\end{matrix}\right.\)
\(...\Rightarrow\left(x-5\right)^2=9^2\Rightarrow\left[{}\begin{matrix}x-5=3\\x-5=-3\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=8\\x=2\end{matrix}\right.\)
\(...\Rightarrow\left(13-x\right)^4=3^4\Rightarrow\left[{}\begin{matrix}13-x=3\\13-x=-3\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=10\\x=16\end{matrix}\right.\)
a) (4x - 1)2 = 25.9
=> (4x - 1)2 = 52 . 32 = 152
=> 4x - 1 = 15
=> 4x = 16
=> x = 4
b) 2x + 2x+3 = 144
=> 2x + 2x . 23 = 144
=> 2x (1 + 23) = 144
=> 2x . 9 = 144
=> 2x = 16
=> x = 4
c) đề chắc chắn đúng chứ :v
d) (2x + 1)3 - 12 = 15
=> (2x + 1)3 = 27
=> (2x + 1)3 = 33
=> 2x + 1 = 3 => 2x = 2 => x = 1
2. 2x = 16 => 2x = 24 => x = 4
3x = 81 => 3x = 34 => x = 4
x3 = 64 => x3 = 43 => x = 4
x2 =81 => x2 = 92 => x = 9
a) \(\left(4x+5\right):3-121:11=4\)
\(\Leftrightarrow\left(\dfrac{4x}{3}+\dfrac{5}{3}\right)-11=4\)
\(\Leftrightarrow\dfrac{4x}{3}+\dfrac{5}{3}-11=4\)
\(\Leftrightarrow\dfrac{4x}{3}+\dfrac{5}{3}-\dfrac{33}{3}=4\)
\(\Leftrightarrow\dfrac{4x}{3}+\dfrac{5-33}{3}=4\)
\(\Leftrightarrow\dfrac{4x}{3}-\dfrac{28}{3}=4\)
\(\Leftrightarrow\dfrac{4x}{3}=4+\dfrac{28}{3}\)
\(\Leftrightarrow\dfrac{4x}{3}=\dfrac{12}{3}+\dfrac{28}{3}\)
\(\Leftrightarrow\dfrac{4x}{3}=\dfrac{12+28}{3}\)
\(\Leftrightarrow\dfrac{4x}{3}=\dfrac{40}{3}\)
\(\Leftrightarrow4x=\dfrac{40}{3}.3\)
\(\Leftrightarrow4x=40\)
\(\Leftrightarrow x=\dfrac{40}{4}=10\)
Vậy \(x=10\)
c) ( 2x + 1 )3 =125
=> (2x+1)3=53
=> 2x+1=5
=> 2x=4
=> x=2
vậy x=2
(4x-1)2=25x9
(4x-1)2=152
=>4x-1=15
4x =16
(4x - 1)2 = 25 . 9
\(\Rightarrow\)(4x - 1) . (4x - 1) = 225
\(\Rightarrow\)(4x - 1) . (4x - 1) = 15 . 15
\(\Rightarrow\)4x - 1 = 15
\(\Rightarrow\)4x = 16
\(\Rightarrow\)x = 4