1)tìm x biết:
a)(x-2)^2=1
b)(2x-1)^3=-8
c)(x+1/2)^2=1/16
d)(x-2)^3=-27
e(2x-3)^2=25
g)3^x-1=1/243
h)2^x+2^x+3=144
k)81^-2x*27^x=95
1)tìm x biết:
a)(x-2)^2=1
b)(2x-1)^3=-8
c)(x+1/2)^2=1/16
d)(x-2)^3=-27
e(2x-3)^2=25
g)3^x-1=1/243
h)2^x+2^x+3=144
k)81^-2x*27^x=95
a. (x - 2)2 = 1
<=> (x - 2)2 = 12 = (-1)2
<=> \(\begin{cases}x-2=1\\x-2=-1\end{cases}\Leftrightarrow\begin{cases}x=3\\x=1\end{cases}\)
Vậy x \(\in\){1; 3}.
b. (2x - 1)3 = -8
<=> (2x - 1)3 = (-2)3
<=> 2x - 1 = -2
<=> 2x = -2 + 1
<=> 2x = -1
<=> x = -1/2
Vậy x = -1/2.
c. (x + 1/2)2 = 1/16
<=> (x + 1/2)2 = (1/4)2 = (-1/4)2
<=> \(\begin{cases}x+\frac{1}{2}=\frac{1}{4}\\x+\frac{1}{2}=-\frac{1}{4}\end{cases}\Leftrightarrow\begin{cases}x=-\frac{1}{4}\\x=-\frac{3}{4}\end{cases}\)
Vậy x \(\in\){-1/4; -3/4}.
d. (x - 2)3 = -27
<=> (x - 2)3 = (-3)3
<=> x - 2 = -3
<=> x = -3 + 2
<=> x = -1
Vậy x = -1.
a.\(\left(x-2\right)^2\)=1
<=> x-2=1 hoặc x-2=-1
<=> x= 3 hoặc x=1
b.\(\left(2x-1\right)^3\)=-8
\(\left(2x-1\right)^3\)=\(\left(-2\right)^3\)
2x-1=-2
2x=-1
x=-1/2
c.\(\left(x+\frac{1}{2}\right)^2\)=\(\frac{1}{16}\)
\(\left(x+\frac{1}{2}\right)^2\)=\(\left(\frac{1}{4}\right)^2\)hoặc \(\left(x+\frac{1}{2}\right)^2\)=\(\left(-\frac{1}{4}\right)^2\)
x+\(\frac{1}{2}\)=\(\frac{1}{4}\) hoặc x+\(\frac{1}{2}\)=-\(\frac{1}{4}\)
x=-\(\frac{1}{4}\)hoặc x=-\(\frac{3}{4}\)
d.\(\left(x-2\right)^3\)=-27
\(\left(x-2\right)^3\)=\(\left(-3\right)^3\)
x-2=-3
x=-1
g.\(3^{x-1}\)=\(\frac{1}{243}\)
\(3^{x-1}\)=\(\frac{1}{3^5}\)
\(3^{x-1}\)=\(3^{-5}\)
x-1=-5
x=-4
bài 1 tìm x biết
a)(-2/3)^2.x=(-2/3)^5
b)(-1/3)^3.x=1/81
c)(x-1)^3=27
d)(2x+1)^2=25
e)(2x-3)^2=36
f)5^x+2=625
g)(x-1)^x+2=(x-1)^x+4
h)(2x-1)^3=-8
k)1/4.2/6.3/8.4/10.5/12....30/62.31/64=2^x
bai2 tim so nguyen duong n biet
a)32<2^n<128
b)2,16>=2^n>4
c)9,27<=3^n<=243
Tìm x:
\(a\)) \(\dfrac{2}{3}+\left(x-\dfrac{1}{2}\right)^3=\dfrac{19}{27}\)
\(b\)) \(\left(\dfrac{3}{2}\right)^{2x-1}:\left(\dfrac{27}{8}\right)^3=\dfrac{81}{16}\)
\(c\)) \(\dfrac{1}{2}.2^x+4.2^x=9.2^5\)
\(d\)) \(\text{12 - (2x +1)}^2=-69\)
\(a,\Rightarrow\left(x-\dfrac{1}{2}\right)^3=\dfrac{1}{27}=\left(\dfrac{1}{3}\right)^3\\ \Rightarrow x-\dfrac{1}{2}=\dfrac{1}{3}\Rightarrow x=\dfrac{5}{6}\\ b,\Rightarrow\left(\dfrac{3}{2}\right)^{2x-1}:\left(\dfrac{3}{2}\right)^9=\left(\dfrac{3}{2}\right)^4\\ \Rightarrow2x-1-9=4\\ \Rightarrow2x=14\Rightarrow x=7\\ c,\Rightarrow2^{x-1}+2^{x+2}=9\cdot2^5\\ \Rightarrow2^{x-1}\left(1+2^3\right)=9\cdot2^5\\ \Rightarrow2^{x-1}\cdot9=9\cdot2^5\\ \Rightarrow2^{x-1}=2^5\Rightarrow x-1=5\Rightarrow x=6\\ d,\Rightarrow\left(2x+1\right)^2=12+69=81\\ \Rightarrow\left[{}\begin{matrix}2x+1=9\\2x+1=-9\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=4\\x=-5\end{matrix}\right.\)
\(a,\dfrac{2}{3}+\left(x-\dfrac{1}{2}\right)^3=\dfrac{19}{27}\)
\(\left(x-\dfrac{1}{2}\right)^3=\dfrac{19}{27}-\dfrac{2}{3}\)
\(\left(x-\dfrac{1}{2}\right)^3=\dfrac{1}{27}\)
\(\Rightarrow\left(x-\dfrac{1}{2}\right)^3=\left(\dfrac{1}{3}\right)^3\)
\(\Rightarrow x-\dfrac{1}{2}=\dfrac{1}{3}\)
\(x=\dfrac{1}{2}+\dfrac{1}{3}\)
\(x=\dfrac{1}{5}\)
tìm x
3^x-1=1/243
81^-2x.27^x=9^5
2^x+2^x+3=144
3^ x -1 = 1/243
3^x =1/243 +1
3^x = 244 / 243
Ta thấy đây ko phải lũy thừa của 3 => Ko có x thỏa mãn
81^-2x . 27^x =9^5
81^-2 . 81^x . 27^x =9^5
1/9^4 . (81.27)^x =9 ^5
3^6x = 9^5 : 1/9^4
3^6x = 9^9
3^6x = 3^18
=> 6x =18
x=3
2^x +2^x +3 =144
2.(2^x) =141
2^x+1 = 141
Ta thấy 141 ko phải lũy thừa của 2 => ko có x thỏa mãn
tìm x biết
a,[x-1]^3=27
b, x^2+x=0
c,[2x=1]=25
d,[2x-3]^2=36
e,5^x+2=625
f,[x-1]^x+2=[x-1]^x+4
g,[2x-1]^3=8
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
a, \(x^2-4x+\dfrac{1}{4}\)
b, \(8x^2-25\)
c, \(x^2+7x=8\)
d, \(x^3-3x=-27+9x\)
e, x(x-3)-7x=-21
f, \(x^3-2x^2+x-2=0\)
g, \(x^2-4x=-4\)
h, \(x^3-x^2+x=-1\)
\(a,=x^2-4x+4-\dfrac{15}{4}=\left(x-2\right)^2-\dfrac{15}{4}=\left(x-2-\dfrac{\sqrt{15}}{2}\right)\left(x-2+\dfrac{\sqrt{15}}{2}\right)\\ b,=?\\ c,\Rightarrow x^2+7x-8=0\\ \Rightarrow\left(x+8\right)\left(x-1\right)=0\Rightarrow\left[{}\begin{matrix}x=-8\\x=1\end{matrix}\right.\\ d,Sửa:x^3-3x^2=-27+9x\\ \Rightarrow x^3-3x^2+9x-27=0\\ \Rightarrow x^2\left(x-3\right)+9\left(x-3\right)=0\\ \Rightarrow\left(x^2+9\right)\left(x-3\right)=0\Rightarrow\left[{}\begin{matrix}x^2=-9\left(vô.lí\right)\\x=3\end{matrix}\right.\\ \Rightarrow x=3\\ e,\Rightarrow x\left(x-3\right)-7x+21=0\\ \Rightarrow x\left(x-3\right)-7\left(x-3\right)=0\\ \Rightarrow\left(x-7\right)\left(x-3\right)=0\Rightarrow\left[{}\begin{matrix}x=7\\x=3\end{matrix}\right.\\ f,\Rightarrow x^2\left(x-2\right)+\left(x-2\right)=0\\ \Rightarrow\left(x^2+1\right)\left(x-2\right)=0\Rightarrow\left[{}\begin{matrix}x^2=-1\left(vô.lí\right)\\x=2\end{matrix}\right.\\ \Rightarrow x=2\)
\(g,\Rightarrow x^2-4x+4=0\\ \Rightarrow\left(x-2\right)^2=0\\ \Rightarrow x=2\\ h,Sửa:x^3-x^2+x=1\\ \Rightarrow x^2\left(x-1\right)+\left(x-1\right)=0\\ \Rightarrow\left(x^2+1\right)\left(x-1\right)=0\Rightarrow\left[{}\begin{matrix}x^2=-1\left(vô.lí\right)\\x=1\end{matrix}\right.\\ \Rightarrow x=1\)
tìm x
a)(1/2) mũ x =1/64
b)9 mũ x :3 mũ x =27
c) 8/2x=2
d)16 /(-2)mũ x =-8
e) 5 mũ 2 .5 mũ x=5 mũ x
g)(x-3)mũ 2 =1
h)(2x-1)mũ 3 = -27
j) 3 mũ -1 .3 mũ x +9 . 3 mũ x = 28
tim x :
a) ( x - 15 ) : 3 = 19
b) ( 5x - 45 ) x 15 = 450
c) 187 - 3( x + 4 ) = 34
d) 9x - 45 = 3^7 : 3^5
e ) ( 12x - 4^3 ) x 8^3 = 4 x 8^4
f ) x^2 = 4 , x^3 = 27
g ) ( x + 1 )^2 = 4
h ) ( 2x - 1 )^2 = 25
k ) ( 2x - 1 )^5 = 243
giup mik nhanh nhat co the nha
a) x = 72
b) x = 15
c) x = 34
d) x = 6
e)
f) x = 2 , x =3
g) x=1,x=-3
h)x=3,x=-2
mik chỉ bt giải thế thôi
CHÚC BẠN HỌC TỐT
Bài làm
a) ( x - 15 ) : 3 = 19
x - 15 = 19 . 3
x - 15 = 57
x = 57 + 15
x = 72
Vậy x = 72.
b) ( 5x - 45 ) . 15 = 450
5x - 45 = 450 : 15
5x - 45 = 30
5x = 75
x = 15
Vậy x = 15.
c) 187 - 3( x + 4 ) = 34
3( x + 4 ) = 187 - 34
3( x + 4 ) = 153
x + 4 = 153 : 3
x + 4 = 51
x = 47
Vậy x = 47.
d) 9x - 45 = 37 : 35
9x - 45 = 32
9x - 45 = 9
9( x - 5 ) = 9
x - 5 = 9 : 9
x - 5 = 1
x = 6
Vậy x = 6.
e ) ( 12x - 43 ) . 83 = 4 . 84
( 12x - 64 ) = 4 . 84 : 83
12x - 64 = 4 . 8
12x - 64 = 32
12x = 96
x = 8
Vậy x = 8.
f ) Đề bài không rõ ràng.
g ) ( x + 1 )2 = 4
=> ( x + 1 )2 = 22
=> x + 1 = 2
=> x = 1
Vậy x = 1.
h ) ( 2x - 1 )2 = 25
=> ( 2x - 1 )2 = 52
=> 2x - 1 = 5
=> 2x = 6
=> x = 3
Vậy x = 3
k ) ( 2x - 1 )5 = 243
=> ( 2x - 1 )5 = 35
=> 2x - 1 = 3
=> 2x = 4
=> x = 2
Vậy x = 2
# Học tốt #
a) ( x - 15 ) : 3 = 19
( x - 15 ) = 19 . 3
x - 15 = 57
x = 57 + 15
x = 72
b) ( 5x - 45 ) x 15 = 450
5x - 45 = 450 : 15
5x - 45 = 30
5x = 30 + 45
5x = 75
c) 187 - 3( x + 4 ) = 34
3( x + 4 ) = 187 - 34
3( x + 4 ) = 153
x + 4 = 153 : 3
x + 4 = 51
x = 51 - 4
x = 47
d) 9x - 45 = 37 : 35
9x - 45 = 32
9x - 45 = 9
9x = 9 + 45
9x = 54
x = 54 : 9
x = 6
e) ( 12x - 43 ) x 83 = 4 x 84
( 12x - 64 ) x 512 = 4 x 4096
( 12x - 64 ) x 512 = 16384
12x - 64 = 16384 : 512
12x - 64 = 32
12x = 32 + 64
12x = 96
x = 96 : 12
x = 8
f) x2 = 4
x2 = 22
=> x = 2
x3 = 27
x3 = 33
=> x = 3
g) ( x + 1 )2 = 4
( x + 1 )2 = 22
=> x + 1 = 2
x = 2 - 1
x = 1
h) ( 2x - 1 )2 = 25
( 2x - 1 )2 = 52
=> 2x - 1 = 5
2x = 5 + 1
2x = 6
x = 6 : 2
x = 3
k) ( 2x - 1 )5 = 243
( 2x - 1 )5 = 35
=> 2x - 1 = 3
2x = 3 + 1
2x = 4
x = 4 : 2
x = 2
Chúc bn hok tốt