tìm số tự nhiên x bt
a)\(2^{4x+1}-8^{x+2}=0\)
b)\(3^2.9^{2x}=27^{x+3}\)
c)\(8^{2x}.64^2=16^{x+4}\)
Tìm x biết
a) (x-3)^2 -4=0
b) ( 2x+3)^2 - (2x+1)(2x-1) =22
c) (4x+3)(4x-3) -(4x-5)^2 =16
d) x^3 -9x^2 +27x-27 =-8
e) (x+1)^3 - x^2(x+3) =2
a) \(\left(x-3\right)^2-4=0\)
\(\left(x-3\right)^2=0+4\)
\(\left(x-3\right)^2=4\)
\(\left(x-3\right)^2=\pm4\)
\(\left(x-3\right)^2=\pm2^2\)
\(\orbr{\begin{cases}x-3=2\\x-3=-2\end{cases}}\)
\(\orbr{\begin{cases}x=5\\x=1\end{cases}}\)
b) \(\left(2x+3\right)^2-\left(2x+1\right)\left(2x-1\right)=22\)
\(4x^2+12x+9-4x^2+1=22\)
\(12x+10=22\)
\(12x=22-10\)
\(12x=12\)
\(x=1\)
c) \(\left(4x+3\right)\left(4x-3\right)-\left(4x-5\right)^2=16\)
\(16x^2-9-16x^2+40x-25=16\)
\(-34+40x=16\)
\(40x=16+34\)
\(40x=50\)
\(x=\frac{50}{40}=\frac{5}{4}\)
d) \(x^3-9x^2+27x-27=-8\)
\(x^3-9x^2+27x-27+8=0\)
\(x^3-9x^2+27x-19=0\)
\(\left(x^2-8x+19\right)\left(x-1\right)=0\)
Vì \(\left(x^2-8x+19\right)>0\) nên:
\(x-1=0\)
\(x=1\)
e) \(\left(x+1\right)^3-x^2\left(x+3\right)=2\)
\(x^3+2x^2+x+x^2+2x+1-x^2-3x^2=2\)
\(3x+1=2\)
\(3x=2-1\)
\(3x=1\)
\(x=\frac{1}{3}\)
Tìm x biết
a) (x-3)^2 -4=0
b) ( 2x+3)^2 - (2x+1)(2x-1) =22
c) (4x+3)(4x-3) -(4x-5)^2 =16
d) x^3 -9x^2 +27x-27 =-8
e) (x+1)^3 - x^2(x+3) =2
b) ( 2x+3)^2 - (2x+1)(2x-1) =22
=> 4x2+12x+9-4x2+1=22
=> 12x=12
=>x=1
c) (4x+3)(4x-3) -(4x-5)^2 =16
=>16x2-9-16x2+40x-25=16
=>40x=50
=>x=4/5
a)\(\left(x-13\right)^2-4=0\\\left(x-13\right)^2=4\\ \left(x-13\right)^2=2^2\\ \Rightarrow\left\{{}\begin{matrix}x-13=2\\x-13=-2\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}15\\-11\end{matrix}\right.\)
vậy...
d) x^3 -9x^2 +27x-27 =-8
=>(x-3)3=-8
=>x-3=-2
=>x=1
e) (x+1)^3 - x^2(x+3) =2
=>x3+3x2+3x+1-x3-3x2=2
=>3x=1
=>x=1/3
1.Tìm số tự nhiên x, biết a) x^3=7^3 b) x^3=27 c) x^3=125 d) ( x+1)^3=125 e) (x-2)^3=2^3 f) (x-2)^3=8 h) (x+2)^2=64 j) (x-3)^6=64 k) 9x^2=36 l) (x-1)^4=16 Giúp tớ vs
a: x^3=7^3
=>x^3=343
=>\(x=\sqrt[3]{343}=7\)
b: x^3=27
=>x^3=3^3
=>x=3
c: x^3=125
=>x^3=5^3
=>x=5
d: (x+1)^3=125
=>x+1=5
=>x=4
e: (x-2)^3=2^3
=>x-2=2
=>x=4
f: (x-2)^3=8
=>x-2=2
=>x=4
h: (x+2)^2=64
=>x+2=8 hoặc x+2=-8
=>x=6 hoặc x=-10
j: =>x-3=2 hoặc x-3=-2
=>x=1 hoặc x=5
k:
9x^2=36
=>x^2=36/9
=>x^2=4
=>x=2 hoặc x=-2
l:
(x-1)^4=16
=>(x-1)^2=4(nhận) hoặc (x-1)^2=-4(loại)
=>x-1=2 hoặc x-1=-2
=>x=3 hoặc x=-1
Bài 4: Tìm x biết
a) (x-3) mũ 2 -4=0
b) (2x+3) mũ 2 - (2x+1)(2x-1)=22
c) (4x+3)(4x-3) - (4x-5) mũ 2=16
d) x mũ 3 - 9x mũ 2 + 27x - 27= -8
e) (x+1) mũ 3 - x mũ 2 nhân (x+3)=2
f) (x-2) mũ 3 - x(x-1)(x+1) + 6x mũ 2=5
a) ( x - 3 )2 - 4 = 0
<=> ( x - 3 )2 - 22 = 0
<=> ( x - 3 - 2 )( x - 3 + 2 ) = 0
<=> ( x - 5 )( x - 1 ) = 0
<=> x = 5 hoặc x = 1
b( 2x + 3 )2 - ( 2x + 1 )( 2x - 1 ) = 22
<=> 4x2 + 12x + 9 - ( 4x2 - 1 ) = 22
<=> 4x2 + 12x + 9 - 4x2 + 1 = 22
<=> 12x + 10 = 22
<=> 12x = 12
<=> x = 1
c) ( 4x + 3 )( 4x - 3 ) - ( 4x - 5 )2 = 16
<=> 16x2 - 9 - ( 16x2 - 40x + 25 ) = 16
<=> 16x2 - 9 - 16x2 + 40x - 25 = 16
<=> 40x - 34 = 16
<=> 40x = 50
<=> x = 50/40 = 5/4
d) x3 - 9x2 + 27x - 27 = -8
<=> ( x - 3 )3 = -8
<=> ( x - 3 )3 = (-2)3
<=> x - 3 = -2
<=> x = 1
e) ( x + 1 )3 - x2( x + 3 ) = 2
<=> x3 + 3x2 + 3x + 1 - x3 - 3x2 = 2
<=> 3x + 1 = 2
<=> 3x = 1
<=> x = 1/3
f) ( x - 2 )3 - x( x - 1 )( x + 1 ) + 6x2 = 5
<=> x3 - 6x2 + 12x - 8 - x( x2 - 1 ) + 6x2 = 5
<=> x3 + 12x - 8 - x3 + x = 5
<=> 13x - 8 = 5
<=> 13x = 13
<=> x = 1
a) \(\left(x-3\right)^2-4=0\)
=> \(\left(x-3\right)^2-2^2=0\)
=> \(\left(x-3-2\right)\left(x-3+2\right)=0\)
=> \(\left(x-5\right)\left(x-1\right)=0\)
=> \(\orbr{\begin{cases}x=5\\x=1\end{cases}}\)
b) \(\left(2x+3\right)^2-\left(2x+1\right)\left(2x-1\right)=22\)
=> \(\left(2x+3\right)^2-\left[\left(2x\right)^2-1^2\right]=22\)
=> \(\left(2x+3\right)^2-\left(4x^2-1\right)=22\)
=> \(\left(2x\right)^2+2\cdot2x\cdot3+3^2-4x^2+1=22\)
=> \(4x^2+12x+9-4x^2+1=22\)
=> \(12x+9+1=22\)
=> \(12x+10=22\)
=> 12x = 12
=> x = 1
c) \(\left(4x+3\right)\left(4x-3\right)-\left(4x-5\right)^2=16\)
=> \(\left(4x\right)^2-3^2-\left[\left(4x\right)^2-2\cdot4x\cdot5+5^2\right]=16\)
=> \(16x^2-9-\left(16x^2-40x+25\right)=16\)
=> \(16x^2-9-16x^2+40x-25=16\)
=> \(-9+40x-25=16\)
=> \(40x=16+25-\left(-9\right)=16+25+9=50\)
=> x = 50/40 = 5/4
d) \(x^3-9x^2+27x-27=-8\)
=> \(x^3-3\cdot x^2\cdot3+3\cdot x\cdot3^2-3^3=8\)
=> \(\left(x-3\right)^3=-8\)
=> \(\left(x-3\right)^3=\left(-2\right)^3\)
=> x - 3 = -2 => x = 1
e) \(\left(x+1\right)^3-x^2\left(x+3\right)=2\)
=> \(x^3+3x^2+3x+1-x^3-3x^2=2\)
=> \(3x+1=2\)
=> \(3x=1\)=> x = 1/3
f) \(\left(x-2\right)^3-x\left(x-1\right)\left(x+1\right)+6x^2=5\)
=> \(x^3-3\cdot x^2\cdot2+3\cdot x\cdot2^2-2^3-x\left(x^2-1\right)+6x^2=5\)
=> \(x^3-6x^2+12x-8-x^3+x+6x^2=5\)
=> \(\left(12x+x\right)-8=5\)
=> 13x = 13
=> x = 1
a) (x+3)^2-4=0
=>(x+3)^2 = 4
=>(x+3)^2 = 2^2 = (-2)^2
=>x+3 = 2 hoặc -2
=> x= -1 hoặc -5
Các bạn giải giúp mk nha:
Bài 1: Tính bằng 2 cách:
a) 25 : 24
b) 34 : 32
c) 63 : 62
d) 84 : 82
e) 75 : 74
f) 1003 : 100
Bài 2: Tìm số tự nhiên x, biết:
a) 2x = 16
b) 3x = 243
c) 5x+1 = 125
d) 5x-1 = 5
e) 42x+1 = 64
f) x17 = x
Bài 3: Tìm số tự nhiên x, biết:
a) 2x : 2 = 8
b) 3x : 32 = 243
c) 625 : 5x = 52
d) 3x : 27 = 9
e) 7x+1 : 7 = 49
f) 112x+1 : 11 = 121
Bài 4: Tìm số tự nhiên x, biết:
a) x2 = 16
b) x3 = 27
c) 2.x3 - 4 = 12
d) 5.x3 - 5 = 0
e) (x + 1)2 = 16
f) (x +1)3 = 27
Mong các bạn giải giúp mk, mk đang rất cần. Thanks mấy bạn trước nhé.
tìm x thuộc số tự nhiên
a)2 mũ x=16 , 2 mũ x =128
b)3 mũ x =27 , 3 mũ x =81
c)4 mũ x=64
d)5 mũ 2x=625
e)6 mũ 2x +1=216
\(2^x=16\Leftrightarrow2^x=2^4\Leftrightarrow x=4\)
\(2^x=128\Leftrightarrow2^x=2^7\Leftrightarrow x=7\)
b), c) tương tự
d) \(5^{2x}=625\Leftrightarrow5^{2x}=5^4\Leftrightarrow2x=4\Leftrightarrow x=2\)
e) tương tự d
Tìm số tự nhiên x :
a) 2x + 3.(x+4) - 14 =8
b) x + 2.x + 3.x = 4.x + 16
c) 2.(x+1) + 3.(x + 5) = 0
d) ( x - 3 ).( x - 5 ) = 0
e) (2x - 40). (15 - 3.x) = 0
f) (3.x+6).(28-2.x) + 13 = 13
a)\(2x+3\left(x+4\right)-14=8\)
\(2x+3x+12-14=8\)
\(2x+3x-2=8\)
\(5x-2=8\)
\(5x=8+2\)
\(5x=10\)
\(x=10:5\)
\(x=2\)
b)\(x+2x+3x=4x+16\)
\(x\left(1+2+3\right)=4x+16\)
\(6x-4x=16\)
\(2x=16\)
\(x=16:2\)
\(x=8\)
c)\(2\left(x+1\right)+3\left(x+5\right)=0\)
\(2x+2+3x+15=0\)
\(5x+17=0\)
\(5x=0-17\)
\(5x=-17\)
\(x=-17:5\)
\(x=-\frac{17}{5}\)
BT2: Tìm x 2, 3x(x-4)+2x-8=0 3, 4x(x-3)+x^2-9=0 4, x(x-1)-x^2+3x=0 5, x(2x-1)-2x^2+5x=16
2: \(3x\left(x-4\right)+2x-8=0\)
=>\(3x\left(x-4\right)+2\left(x-4\right)=0\)
=>\(\left(x-4\right)\left(3x+2\right)=0\)
=>\(\left[{}\begin{matrix}x-4=0\\3x+2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=4\\x=-\dfrac{2}{3}\end{matrix}\right.\)
3: 4x(x-3)+x2-9=0
=>\(4x\left(x-3\right)+\left(x+3\right)\left(x-3\right)=0\)
=>\(\left(x-3\right)\left(4x+x+3\right)=0\)
=>\(\left(x-3\right)\left(5x+3\right)=0\)
=>\(\left[{}\begin{matrix}x-3=0\\5x+3=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{3}{5}\end{matrix}\right.\)
4: \(x\left(x-1\right)-x^2+3x=0\)
=>\(x^2-x-x^2+3x=0\)
=>2x=0
=>x=0
5: \(x\left(2x-1\right)-2x^2+5x=16\)
=>\(2x^2-x-2x^2+5x=16\)
=>4x=16
=>x=4
1: =>5(2x+6)=40
=>2x+6=8
=>2x=2
=>x=1
2: =>12-(x+3)=256:64=4
=>(x+3)=8
=>x=5
3: =>2x-1=3 hoặc 2x-1=-3
=>x=2 hoặc x=-1
4: \(\Leftrightarrow3^{x+2017}=3^{2015}\)
=>x+2017=2015
=>x=-2
1: =>5(2x+6)=40
=>2x+6=8
=>2x=2
=>x=1
2: =>12-(x+3)=256:64=4
=>(x+3)=8
=>x=5
3: =>2x-1=3 hoặc 2x-1=-3
=>x=2 hoặc x=-1
4:
=>x+2017=2015
=>x=-2