a)|-x+2/5|+1/2=3,5 b)21/5+3:|x/4-2/3|=6
c)7,5-3|5-2x|=-4,5 d)1/3-|5/4-2x|=1/4
e)21/5+3:|x/4-2/3|=6
a)|-x+2/5|+1/2=3,5 b)21/5+3:|x/4-2/3|=6
c)7,5-3|5-2x|=-4,5 d)1/3-|5/4-2x|=1/4
e)21/5+3:|x/4-2/3|=6
a: Ta có: \(\left|\dfrac{2}{5}-x\right|+\dfrac{1}{2}=3.5\)
\(\Leftrightarrow\left|x-\dfrac{2}{5}\right|=3\)
\(\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{2}{5}=3\\x-\dfrac{2}{5}=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{17}{5}\\x=-\dfrac{13}{5}\end{matrix}\right.\)
b: Ta có: \(\dfrac{21}{5}+3:\left|\dfrac{x}{4}-\dfrac{2}{3}\right|=6\)
\(\Leftrightarrow3:\left|\dfrac{1}{4}x-\dfrac{2}{3}\right|=6-\dfrac{21}{5}=\dfrac{9}{5}\)
\(\Leftrightarrow\left|\dfrac{1}{4}x-\dfrac{2}{3}\right|=\dfrac{5}{3}\)
\(\Leftrightarrow\left[{}\begin{matrix}\dfrac{1}{4}x-\dfrac{2}{3}=\dfrac{5}{3}\\\dfrac{1}{4}x-\dfrac{2}{3}=-\dfrac{5}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}\dfrac{1}{4}x=\dfrac{7}{3}\\\dfrac{1}{4}x=-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{28}{3}\\x=-4\end{matrix}\right.\)
tìm x
a, | 5/4x - 7/2 | - | 5/8x + 3/5 | = 0
b, 21/5 + 3 : | x/4 - 2/3 | = 6
c,| 9 + x | = 2x
d, | 2x - 3 | + x = 21
e, | 7 - 2x | + 7 = 2x
f, | -x + 2/5 | + 1/2 = 3,5
G, | 3x - 4 | + 4 = 3x
a) | 5/4x -7/2| - | 5/8x + 3/5| = 0
|5/4x - 7/2| = | 5/8x + 3/5|
TH1: 5/4x - 7/2 = 5/8x + 3/5
=> 5/4x - 5/8x = 3/5 +7/2
5/8x = 41/10
x = 41/10:5/8
x = 164/25
TH2: 5/4x - 7/2 = -5/8x - 3/5
=> 5/4x + 5/8x = -3/5 +7/2
15/8x = 29/10
x = 29/10 : 15/8
x = 116/75
KL: x = 164/25 hoặc x = 116/75
các bài cn lại b lm tương tự nha! h lm dài lắm!
tìm x
a, | 5/4x - 7/2 | - | 5/8x + 3/5 | = 0
b, 21/5 + 3 : | x/4 - 2/3 | = 6
c,| 9 + x | = 2x
d, | 2x - 3 | + x = 21
e, | 7 - 2x | + 7 = 2x
f, | -x + 2/5 | + 1/2 = 3,5
G, | 3x - 4 | + 4 = 3x
a: =>|5/4x-7/2|=|5/8x+3/5|
=>5/4x-7/2=5/8x+3/5 hoặc 5/4x-7/2=-5/8x-3/5
=>5/8x=41/10 hoặc 15/8x=29/10
=>x=164/25 hoặc x=116/75
b: =>3:|x/4-2/3|=6-21/5=9/5
=>|1/4x-2/3|=5/3
=>1/4x-2/3=5/3 hoặc 1/4x-2/3=-5/3
=>1/4x=7/3 hoặc 1/4x=-1
=>x=28/3 hoặc x=-4
c: \(\Leftrightarrow\left\{{}\begin{matrix}x>=0\\\left(2x-x-9\right)\left(2x+x+9\right)=0\end{matrix}\right.\Leftrightarrow x=9\)
e: =>|2x-7|=2x-7
=>2x-7>=0
=>x>=7/2
a) |x-1/3|=11/5 b)2|2x-3|=1/2
c)2|3x-1|+1=5 d)3/2+4/5|x-3/4|=7/4
e)|2x-5|=4 f)|x/2-1|=3
a)\(\left|\dfrac{x-1}{3}\right|=\dfrac{11}{5}\Rightarrow\dfrac{x-1}{3}=\pm\dfrac{11}{5}\\ \Rightarrow\left[{}\begin{matrix}\dfrac{x-1}{3}=\dfrac{11}{5}\\\dfrac{x-1}{3}=-\dfrac{11}{5}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x-1=\dfrac{33}{5}\\x-1=\dfrac{-33}{5}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\dfrac{38}{5}\\x=\dfrac{-28}{5}\end{matrix}\right.\)
b)\(2\left|2x-3\right|=\dfrac{1}{2}\\ \Rightarrow\left|2x-3\right|=\dfrac{1}{4}\\ \Rightarrow2x-3=\pm\dfrac{1}{4}\\ \Rightarrow\left[{}\begin{matrix}2x-3=\dfrac{1}{4}\\2x-3=-\dfrac{1}{4}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}2x=\dfrac{13}{4}\\2x=\dfrac{-11}{4}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\dfrac{13}{8}\\x=\dfrac{-11}{8}\end{matrix}\right.\)
(x+2)(x+3)-(x-2)(x+5)=0
b)(3x-1)(2x+7)-(x+1(6x-5)
c)(10x+9x)x-(5x-1)(2x+30=8
d)x(2x-1)(x+5)-(2x2+1)(x+4,5)=3,5
e)(2x+3)(x-4)+(x-5)(x-2)=(3x-5)(x-4)
1 Tính Nhanh
a) (-3/4+2/5):3/4+(3/5+ -1/4):3/7
b) (-2/5 x 0,375 x 94) - [ 0,125 x 3,25 x (-8)]
2 Tìm X
a) 1/3 + 1/2 : x = (-4)
b) | x - 3,5 | + 1 = 7,5
c) | x - 2 | = 6 - x
d) x2 - 2x > 0
x2 là x mũ 2 đấy nhé!
BT6:
A) (5x+1)^2=16/25
B) ( x - 1/3)^3=(2/3)^6
C)(8x - 1)^4=(2x+7)^4
D) (x -1)^5 =(2x-3)^5
E) ( x +1 )^8=(x+1)^10
G) (21-3)^4+(x+5)^6=0
H) 3x -4 = 81^3
a) (5x+1) ^ 2 = 4^2 : 5^ 2
( 5x+1) ^2 = (4:5) ^2
=> (5x+1) = ( 4 : 5) = 0.8
5x = 0.8 - 1
x = 0.7 : 5
x = 0,14
a,x - 1/2 - (-1/6)
b,x + 5/6 = 3/8
c,2/3 . x -1/2 = 5/6
d, x/7 = 6/-21
e,(7/3 x -0,6) : 3^2/5 = 1
f,x/45 = 5/6 + -29/30
g,(4,5 - 2x) . (-1^4/7) =11/14
h,-2/7 + 4/7x=5/7
b: \(x+\dfrac{5}{6}=\dfrac{3}{8}\)
=>\(x=\dfrac{3}{8}-\dfrac{5}{6}\)
=>\(x=\dfrac{9}{24}-\dfrac{20}{24}=-\dfrac{11}{24}\)
c: \(\dfrac{2}{3}x-\dfrac{1}{2}=\dfrac{5}{6}\)
=>\(\dfrac{2}{3}x=\dfrac{5}{6}+\dfrac{1}{2}=\dfrac{8}{6}=\dfrac{4}{3}\)
=>2x=4
=>x=4/2=2
d: \(\dfrac{x}{7}=\dfrac{6}{-21}\)
=>\(\dfrac{x}{7}=\dfrac{-2}{7}\)
=>x=-2
e: \(\left(\dfrac{7}{3}x-0,6\right):\dfrac{3^2}{5}=1\)
=>\(\dfrac{7}{3}x-0,6=\dfrac{3^2}{5}=1,8\)
=>\(\dfrac{7}{3}x=2,4\)
=>\(x=2,4:\dfrac{7}{3}=2.4\cdot\dfrac{3}{7}=\dfrac{7.2}{7}=\dfrac{36}{35}\)
f: \(\dfrac{x}{45}=\dfrac{5}{6}+\dfrac{-29}{30}\)
=>\(\dfrac{x}{45}=\dfrac{25}{30}-\dfrac{29}{30}=-\dfrac{4}{30}=-\dfrac{2}{15}\)
=>\(x=-\dfrac{2}{15}\cdot45=-6\)
g: \(\left(4,5-2x\right)\cdot\left(-\dfrac{1^4}{7}\right)=\dfrac{11}{14}\)
=>\(4,5-2x=\dfrac{11}{14}:\dfrac{-1}{7}=\dfrac{-11}{2}\)
=>\(2x=4,5+\dfrac{11}{2}=\dfrac{20}{2}=10\)
=>x=10/2=5
h: \(-\dfrac{2}{7}+\dfrac{4}{7}x=\dfrac{5}{7}\)
=>\(\dfrac{4}{7}x=\dfrac{5}{7}+\dfrac{2}{7}=\dfrac{7}{7}\)
=>4x=7
=>\(x=\dfrac{7}{4}\)
Tìm x
a) ( 2,8x - 32 ) : 2/3 = -90
b) 7,5 x 1/3/4x = 6/2/5
c) ( 4,5 - 2x ) : 3/4 = 1/1/3
d) -5/6 + 8/3 + (-29)/6 ≤ x ≤ -1/2 + 2 + 5/2
e) ( 2,7x - 1/1/2x ) : 2/7 = -21/4
Tìm a, b biết :
a/27 = -5/9 = -45/b
\(\frac{a}{27}=\frac{-5}{9}=\frac{-45}{b}\)
\(=>\frac{a.3}{81}=\frac{-45}{81}=\frac{-45}{b}\)
=>b=81
a.3=-45
a=-15
Vậy a=-15;b=81