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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!
\(1,2x+3x-4x=\left(-2\right)^3\)
<=>\(x=-8\)
\(2,x-2x=4^2+4^0\)
<=>\(-x=16+1\)
<=>\(-x=17\)
<=>\(x=-17\)
\(3,2^3x-3^2x=|12-21|\)
<=>\(-x=9\)
<=>\(x=-9\)
\(4,x-45=2x+54\)
<=>\(x-2x=54+45\)
<=>\(-x=99\)
<=>\(x=-99\)
\(5,5x-12+23=6^7:6^5\)
<=>\(5x+11=6^2\)
<=>\(5x+11=36\)
<=>\(5x=25\)
<=>\(x=5\)
1) 4x-(2x-5)=21
4x-2x+5=21
2x+5=21
2x=21 -5
2x=16
x=16/2
x=8
\((x-6)(3x-9)>0\)
TH1:
\(\orbr{\begin{cases}x-6< 0\\3x-9< 0\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}x< 6\\x< 3\end{cases}}\)\(\Rightarrow x< 3\)
TH2:
\(\orbr{\begin{cases}x-6>0\\3x-9>0\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}x>6\\x>3\end{cases}}\)\(\Rightarrow x>6\)
Vậy \(x< 3\) hoặc \(x>6\)thì \((x-6)(3x-9)>0\)
Học tốt!
20.
\((2x-1)(6-x)>0\)
TH1:
\(\orbr{\begin{cases}2x-1>0\\6-x>0\end{cases}\Rightarrow\orbr{\begin{cases}x< \frac{1}{2}\\x< 6\end{cases}}\Rightarrow x< 6}\)
TH2
\(\orbr{\begin{cases}2x-1< 0\\6-x< 0\end{cases}\Rightarrow\orbr{\begin{cases}x>\frac{1}{2}\\x>6\end{cases}}\Rightarrow x>\frac{1}{2}}\)
Vậy \(x< 6\)hoặc \(x>\frac{1}{2}\)thì \((2x-1)(6-x)>0\)
1) 3x - 6= 5x + 2
5x - 3x = -6 - 2
2x = -8
x = -4
2) 15 - x = 4x - 5
4x + x = 15 + 5
5x = 20
x = 4
Tương tự như trên
1) -3-(-x) =5
=> -3 + x = 5
=> x = 5 - (-3)
=> x = 8
2)-9-(x-3)=12
=> x- 3 = (-9) - 12
=> x-3 =-21
=> x = (-21)+3
=> x = -18
3)-10-(x-5)=-5
x-5 = (-10) -(-5)
x-5 = -5
x = -5 +5
x = 0
4)210-(10-x) =110
10-x = 210 -110
10-x = 100
x = 10 -100
x = -90
5)4x-(2x-5)=21
=> 4x-2x + 5 =21
=> x(4-2) + 5 = 21
=> x.2 =21 - 5
=> x.2 = 16
=> x = 16:2
=> x = 8
6)14x-5=8x+10
7)15+5x =3x+30
8)2x-5=15-3x
9)2(3x+5)+3(x+1)=x+220
10)4.(x-2+5(x-3)=18
a, (19-51)-(x-23)=-6
19-51-x+23=-6
-32-x+23=-6
-32-x=-6-23
-32-x=-29
x=-32+(-29)
x=-61
-5x-10(-7)=55
-5x+70=55
-5x=55-70
-5x=-15
x=-15:(-5)
x=3
c, -7-2x=-37-(-26)
-7-2x=-37+26
-7-2x=11
-2x=11+7
-2x=18
x=-9
d, /2x-1/=/-5/
2x-1=5
2x=5+1
2x=6
x=6:2
x=3
e, 2-/x+5/=7
2-x+5=7
2-x=7-5
2-x=2
x=2-2
x=0
h, (x+8)2=25
(x+8)2=52
x+8=5
x=5-8
x=-3
f, (x+3)3:3-1=-10
(x+3)3:3=-10+1
(x+3)3:3=-9
(x+3)3:3=33
x+3:3=3
x+3=9
x=9-3
x=6
k mk nhe
5/2+x=-3/5
x=-3/5-5/2
x=-31/10
vậy x=-31/10
-2x+5=23
-2x=23-5
-2x=18
x=18:-2
x=-9
vậy x=-9
Bài làm :
\(\frac{5}{2}+x=-3,5\)
\(\Leftrightarrow x=-3,5-\frac{5}{2}=-6\)
\(-2x+5=23\)
\(\Leftrightarrow-2x=18\)
\(\Leftrightarrow x=-9\)
\(\frac{x}{21}=\frac{2}{7}-\frac{4}{3}\)
\(\Leftrightarrow\frac{x}{21}=-\frac{22}{21}\)
\(\Leftrightarrow x=-22\)
\(\frac{5}{3}x-\frac{2}{5}x=\frac{19}{10}\)
\(\Leftrightarrow x\left(\frac{5}{3}-\frac{2}{5}\right)=\frac{19}{10}\)
\(\Leftrightarrow\frac{19}{15}x=\frac{19}{10}\)
\(\Leftrightarrow x=\frac{3}{2}\)
Chúc bạn học tốt !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!