Tìm x
A.-2/3.x=(-1/2)^2
B.x÷(-2/5)^3=-2/5
C.2^x=32
D.16/2^x=2
E. (x-2)^2=9
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a: =>x^2-25-x^2-3x=10
=>-3x=35
=>x=-35/3
b: =>4x^2-9-4(x^2+4x+4)=5
=>4x^2-9-4x^2-16x-16-5=0
=>-16x-30=0
=>x=-15/8
c: =>9x^2+45x-9x^2+4=7
=>45x=3
=>x=1/15
d: =>x^3+3x^2+3x+1-x^3-3x^2+5x=8
=>8x=7
=>x=7/8
a: =>x+7/4=6:2/3=9
=>x=29/4
b: =>x:5/3=7/5
=>x=7/5*5/3=7/3
c:=>x+1/6=5/3
=>x=10/6-1/6=3/2
d: =>x+4/5=4/5+3/7+3/5
=>x=3/7+3/5=36/35
e: =>x/35=4/5-5/7=3/35
=>x=3
f: =>13/28+x=1/2
=>x=1/28
g: =>1/3-x=1/9
=>x=2/9
a, đk : x khác -1 ; x khác 2
\(\Rightarrow4x-8=3x+3\Leftrightarrow x=11\left(tm\right)\)
b, đk : x khác 2 ; -2
\(\Rightarrow\left(x+2\right)^2-8x=0\Leftrightarrow\left(x-2\right)^2=0\Leftrightarrow x=2\left(ktm\right)\)
-> vậy pt vô nghiệm
c, đk : x khác 3 ; 0
\(\Rightarrow x-5\left(x-3\right)=3x+7\Leftrightarrow-4x+15=3x+7\Leftrightarrow-7x=-8\Leftrightarrow x=\dfrac{8}{7}\left(tm\right)\)
a)Với \(x\ne-1;x\ne2\)
\(\dfrac{4}{x+1}=\dfrac{3}{x-2}\)
<=>4(x-2)=3(x+1)
<=>4x-8=3x+3
<=>x=11(TM)
b)Với\(x\ne\pm2\)
\(\dfrac{x+2}{2x-4}-\dfrac{4x}{x^2-4}=0\)
<=>\(\dfrac{x+2}{2\left(x-2\right)}-\dfrac{4x}{\left(x+2\right)\left(x-2\right)}=0\)
<=>\(\dfrac{\left(x+2\right)^2-8x}{2\left(x+2\right)\left(x-2\right)}=0\)
<=>\(x^2+4x+4-8x=0\left(Vĩx\ne\pm2\right)\)
<=>\(x^2-4x+4=0\)
<=>\(\left(x-2\right)^2=0\)
<=>x-2=0
<=>x=2(Không thỏa mãn)
c)Với \(x\ne3,x\ne0\)
\(\dfrac{1}{x-3}-\dfrac{5}{x}=\dfrac{3x+7}{x\left(x-3\right)}\)
<=>\(\dfrac{x-5\left(x-3\right)}{x\left(x-3\right)}=\dfrac{3x+7}{x\left(x-3\right)}\)
<=>x-5x+15=3x+7(Vì \(x\ne0,x\ne3\))
<=>7x=8
<=>x=\(\dfrac{8}{7}\left(TM\right)\)
2:
a: =>x-1/5=2/15
=>x=2/15+3/15=5/15=1/3
b: =>x+7/12=-5/6-2/6=-7/6
=>x=-14/12-7/12=-21/12=-7/4
c: =>x+2/3=-10/3
=>x=-4
d: =>1/4:x=-11/4
=>x=-1/4:11/4=-1/11
e: =>8:x=1,6
=>x=5
a, \(\left(x^2-5x+7\right)^2-\left(2x-5\right)^2=0\)
\(\Leftrightarrow\left(x^2-5x+7-2x+5\right)\left(x^2-5x+7+2x-5\right)=0\)
\(\Leftrightarrow\left(x^2-7x+12\right)\left(x^2-3x+2\right)=0\)
\(\Leftrightarrow\left(x-4\right)\left(x-3\right)\left(x-1\right)\left(x-2\right)=0\Leftrightarrow x=1;x=2;x=3;x=4\)
Vậy tập nghiệm phương trình là S = { 1 ; 2 ; 3 ; 4 }
b, \(\left|2x-1\right|=5\Leftrightarrow\left[{}\begin{matrix}2x-1=5\\2x-1=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)
Vậy tập nghiệm của phương trình là S = { -2 ; 3 }
c, \(\left|2x-1\right|=\left|x+5\right|\Leftrightarrow\left(2x-1\right)^2=\left(x+5\right)^2\)
\(\Leftrightarrow\left(2x-1\right)^2-\left(x+5\right)^2=0\Leftrightarrow\left(2x-1-x-5\right)\left(2x-1+x+5\right)=0\Leftrightarrow x=6;x=-\dfrac{4}{3}\)
Vậy tập nghiệm của phương trình là S = { -4/3 ; 6 }
d, \(\left|3x+1\right|=x-2\)
TH1 : \(3x+1=x-2\Leftrightarrow2x=-3\Leftrightarrow x=-\dfrac{3}{2}\)
TH2 : \(3x+1=-x+2\Leftrightarrow4x=1\Leftrightarrow x=\dfrac{1}{4}\)
Vậy tập nghiệm của phương trình là S = { -3/2 ; 1/4 }
các ý còn lại tương tự
a) Ta có: \(\left(x^2-5x+7\right)^2-\left(2x-5\right)^2=0\)
\(\Leftrightarrow\left(x^2-5x+7-2x+5\right)\left(x^2-5x+7+2x-5\right)=0\)
\(\Leftrightarrow\left(x^2-7x+12\right)\left(x^2-3x+2\right)=0\)
\(\Leftrightarrow\left(x-3\right)\left(x-4\right)\left(x-1\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-3=0\\x-4=0\\x-1=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=4\\x=1\\x=2\end{matrix}\right.\)
Vậy: S={3;4;1;2}
a)\(=\dfrac{3}{3}+\dfrac{4}{3}=\dfrac{7}{3}\)
b)\(=\dfrac{5}{9}\times\dfrac{3}{2}=\dfrac{15}{18}=\dfrac{5}{6}\)
d)\(=\left(\dfrac{12}{8}-\dfrac{3}{8}\right)\times2=\dfrac{9}{8}\times2=\dfrac{18}{8}=\dfrac{9}{4}\)
c)\(=\dfrac{4}{3}-\dfrac{5}{6}=\dfrac{8}{6}-\dfrac{5}{6}=\dfrac{3}{6}=\dfrac{1}{2}\)
a) 1 + 4/3 = 7/3
b) 5/9 : 2/3 = 5/6
c ) 4/3 -1/3 x 5/2
= 1 x 5/2
= 5/2
d) ( 3/2 - 3/8) : 1/2
= 9/8 : 1/2
= 9/4
e) 15/16 : 3/8 x 3/4
= 5/2 x 3/4
= 15/8
f) 7/19 x 1/3 x 7/19 x 2/3
= 7/19 x (1/3 x 2/3)
= 7/19 x 2/9
= 14/171
g) 3/5 x 8/27 x 25/3
= 3/5 x 25/3 x 8/27
= 5 x 8/27
= 40/27
h) 1/5 + 4/11 + 4/5 + 7/11
= (1/5 + 4/5) + (4/11 + 7/11)
= 1 + 1
= 2
a) (x+3)^2 - (2-x)^2 = 1
x^2 + 6x + 9 - (4 - 4x + x^2) = 1
x^2 + 6x + 9 - 4 + 4x - x^2 = 1
10x + 5 = 1
10x = -4
x = -4/10
x = -2/5
Vậy giá trị của x là -2/5.
b) 5(x-2)^2 - (x+3)^2 = (2x-1)^2
5(x^2 - 4x + 4) - (x^2 + 6x + 9) = 4x^2 - 4x + 1
5x^2 - 20x + 20 - x^2 - 6x - 9 = 4x^2 - 4x + 1
4x^2 - 26x + 30 = 4x^2 - 4x + 1
-26x + 30 = -4x + 1
-22x = -29
x = 29/22
Vậy giá trị của x là 29/22.
c) (x-1)^2 - x(x+5)^2 = 7
x^2 - 2x + 1 - x(x^2 + 10x + 25) = 7
x^2 - 2x + 1 - x^3 - 10x^2 - 25x = 7
-x^3 - 9x^2 - 27x - 6 = 0
d) (3x-2)^2 - 9(x+2)^2 = 3
9x^2 - 12x + 4 - 9x^2 - 36x - 36 = 3
-48x - 32 = 3
-48x = 35
x = -35/48
Vậy giá trị của x là -35/48.
Giải:
a) \(2^5=4^x\)
\(\Rightarrow2^5=\left(2^2\right)^x\)
\(\Rightarrow2^5=2^{2x}\)
\(\Rightarrow2x=5\)
\(\Rightarrow x=\dfrac{5}{2}\)
b) \(2.4^2.8^3.16^4=8^x\)
\(\Rightarrow2.\left(2^2\right)^2.\left(2^3\right)^3.\left(2^4\right)^4=\left(2^3\right)^x\)
\(\Rightarrow2.2^4.2^9.2^{16}=2^{3x}\)
\(\Rightarrow2^{30}=2^{3x}\)
\(\Rightarrow3x=30\)
\(\Rightarrow x=30:3\)
\(\Rightarrow x=10\)
c) \(3^3:3^5=9^x\)
\(\Rightarrow3^{-2}=\left(3^2\right)^x\)
\(\Rightarrow3^{-2}=3^{2x}\)
\(\Rightarrow2x=-2\)
\(\Rightarrow x=-2:2\)
\(\Rightarrow x=-1\)
Chúc bạn học tốt!
a) Ta có: \(2^5=4^x\)
nên \(2^{2x}=2^5\)
\(\Leftrightarrow2x=5\)
hay \(x=\dfrac{5}{2}\)
b) Ta có: \(2\cdot4^2\cdot8^3\cdot16^4=8^x\)
\(\Leftrightarrow2^{3x}=2\cdot2^5\cdot2^9\cdot2^{16}=2^{31}\)
\(\Leftrightarrow3x=31\)
hay \(x=\dfrac{31}{3}\)
c) Ta có: \(3^3:3^5=9^x\)
\(\Leftrightarrow3^{-2}=3^{2x}\)
\(\Leftrightarrow2x=-2\)
hay x=-1
a) \(-\frac{2}{3}x=\left(-\frac{1}{2}\right)^2\)
\(\Leftrightarrow-\frac{2}{3}x=\frac{1}{4}\)
\(\Rightarrow x=-\frac{3}{8}\)
b) \(x\div\left(-\frac{2}{5}\right)^3=-\frac{2}{5}\)
\(\Leftrightarrow x=\left(\frac{2}{5}\right)^4\)
\(\Rightarrow x=\frac{16}{625}\)
c) \(2^x=32\)
\(\Leftrightarrow2^x=2^5\)
\(\Rightarrow x=5\)
d) \(\frac{16}{2^x}=2\)
\(\Leftrightarrow2^x=8=2^3\)
\(\Rightarrow x=3\)
e) \(\left(x-2\right)^2=9\)
\(\Leftrightarrow\orbr{\begin{cases}x-2=3\\x-2=-3\end{cases}}\Rightarrow\orbr{\begin{cases}x=5\\x=-1\end{cases}}\)
a, \(-\frac{2}{3}x=\left(-\frac{1}{2}\right)^2\Leftrightarrow-\frac{2}{3}x=\frac{1}{4}\Leftrightarrow x=-\frac{3}{8}\)
b, \(\frac{x}{-2,5^3}=-\frac{2}{5}\Leftrightarrow5x=\frac{125}{4}\Leftrightarrow x=\frac{25}{4}\)
c, \(2^x=32\Leftrightarrow2^x=2^5\Leftrightarrow x=5\)
d, mk chưa hiểu đề lăm
e, \(\left(x-2\right)^2=9\Leftrightarrow\orbr{\begin{cases}x-2=3\\x-2=-3\end{cases}\Leftrightarrow\orbr{\begin{cases}x=5\\x=-1\end{cases}}}\)