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a) \(\frac{3}{2}-\left(x-\frac{7}{3}\right)=\left|-\frac{3}{4}-\frac{9}{8}\right|\)
=> \(\frac{3}{2}-x+\frac{7}{3}=\left|-\frac{15}{8}\right|\)
=> \(\frac{3}{2}-x+\frac{7}{3}=\frac{15}{8}\)
=> \(\frac{3}{2}-x=-\frac{11}{24}\)
=> \(x=\frac{47}{24}\)
b) \(\frac{5}{2}-\left(\frac{3}{2}-\frac{7}{3}+x\right)=\frac{8}{15}-\left(\frac{1}{4}-\frac{7}{10}\right)\)
=> \(\frac{5}{2}-\frac{3}{2}+\frac{7}{3}-x=\frac{8}{15}-\left(-\frac{9}{20}\right)\)
=> \(\frac{10}{3}-x=\frac{59}{60}\)
=> \(x=\frac{10}{3}-\frac{59}{60}=\frac{47}{20}\)
c) \(2\left(\frac{3}{4}-5x\right)=\frac{4}{5}-3x\)
=> \(\frac{3}{2}-10x-\frac{4}{5}+3x=0\)
=> \(\left(\frac{3}{2}-\frac{4}{5}\right)+\left(-10x+3x\right)=0\)
=> \(\frac{7}{10}-7x=0\)
=> \(7x=\frac{7}{10}\)
=> x = 1/10
a. 3/5 . 15/7 - 15/7 . 8/5
= 15/7(3/5-8/5)
=15/7. -\(\frac{1}{1}\)
=22/7
b. 4/5 . 1 3/7 + 4/5 . 4/7
=4/5(13/7+4/7)
=4/5.17/7
= 68/35
c: =>2/3x=1/10+1/2=1/10+5/10=6/10=3/5
hay \(x=\dfrac{3}{5}:\dfrac{2}{3}=\dfrac{9}{10}\)
d: \(\Leftrightarrow\dfrac{4}{9}:x=\dfrac{2}{3}-\dfrac{3}{5}=\dfrac{1}{15}\)
hay \(x=\dfrac{4}{9}:\dfrac{1}{15}=\dfrac{4}{9}\cdot15=\dfrac{20}{3}\)
f: (x+1/2)(2/3-2x)=0
=>x+1/2=0 hoặc 2/3-2x=0
=>x=-1/2 hoặc x=1/3
a) 2(x - 5) - 3(x + 7) = 14
<=> 2x - 10 - 3x - 21 = 14
<=> 2x - 3x = 14 + 10 + 21
<=> x = -45
Vậy x = -45
b) 5(x - 6) - 2(x + 3) = 12
<=> 5x - 30 - 2x - 6 = 12
<=> 5x - 2x = 12 + 30 + 6
<=> 3x = 48
<=> x = 16
Vậy x = 16
c) 3(x - 4) - (8 - x) = 12
<=> 3x - 12 - 8 + x = 12
<=> 3x + x = 12 + 12 + 8
<=> 4x = 32
<=> x = 8
Vậy x = 8
d) -7(3x - 5) + (7x - 14) = 28
<=> -21x + 35 + 7x - 14 = 28
<=> -21x + 7x = 28 - 35 + 14
<=> -14x = 7
<=> x = -1/2
Vậy x = -1/2
\(a,2\left(x-5\right)-3\left(x+7\right)=14\)
\(\Leftrightarrow2x-10-3x-21=14\)
\(\Leftrightarrow-x=45\)
\(\Leftrightarrow x=-45\)
\(b,5\left(x-6\right)-2\left(x+3\right)=12\)
\(\Leftrightarrow5x-30-2x-6=12\)
\(\Leftrightarrow3x=48\)
\(\Leftrightarrow x=16\)
\(c,3\left(x-4\right)-\left(8-x\right)=12\)
\(\Leftrightarrow3x-12-8+x=12\)
\(\Leftrightarrow4x=32\)
\(\Leftrightarrow x=8\)
\(d,-7\left(3x-5\right)+2\left(7x-14\right)=28\)
\(\Leftrightarrow-21x+35+14x-28=28\)
\(\Leftrightarrow-7x=21\)
\(\Leftrightarrow x=-3\)
a,\(15-\left(-4-x\right)=6\)
\(\Leftrightarrow-4-x=15-6\)
\(\Leftrightarrow-4-x=9\)
\(\Leftrightarrow x=-4-9\)
\(\Leftrightarrow x=-13\)
b,\(-30+\left(25-x\right)=-1\)
\(\Leftrightarrow25-x=-1-\left(-30\right)\)
\(\Leftrightarrow25-x=29\)
\(\Leftrightarrow x=25-29=-4\)
c,\(x-\left(12-25\right)=-8\)
\(\Leftrightarrow x+13=-8\)
\(\Leftrightarrow x=-21\)
e,\(x-5=1\Rightarrow x=6\)
g,\(x+30=-4\)
\(\Leftrightarrow x=-4-30\)
\(\Leftrightarrow x=-34\)
h,\(x-\left(-24\right)=3\)
\(\Leftrightarrow x+24=3\)
\(\Leftrightarrow x=3-24\)
\(\Leftrightarrow x=-21\)
i,\(\left(x+5\right)+\left(x-9\right)=x+2\)
\(\Leftrightarrow x+5+x-9-x-2=0\)
\(\Leftrightarrow x-6=0\)
\(\Leftrightarrow x=6\)
k,\(\left(27-x\right)+\left(15+x\right)=x-24\)
\(\Leftrightarrow27-x+15+x-x+24=0\)
\(\Leftrightarrow-x+66=0\)
\(\Leftrightarrow-x=-66\)
\(\Leftrightarrow x=66\)
a) 15-(-4-x)=6
15 + 4 + x = 6
19 + x = 6
x = 6 - 19
x = 6 + ( -19 )
x = -13
b) -30+( 25- x ) =-1
25- x = -1 - ( - 30 )
25- x = -1 + 30
25- x =29
x = 25 - 29
x = 25 + ( -29 )
x = -4
c) x- ( 12-25) =-8
x - ( - 13 ) = -8
x + 13 = -8
x = -8 - 13
x = -8 + ( -13 )
x = - 21
d) ( x-29 ) - (17- 38 ) = -9
( x-29) - (-21 ) = -9
x -29 = -9 + ( -21 )
x -29 = -30
x = -30 + 29
x = -1
e) x-5=1
x = 1 + 5
x = 6
g) x + 30 = -4
x = -4 - 30
x = -4 + ( -30 )
x = -34
h) x- ( -24 ) = 3
x = 3 + ( -24 )
x = -21
l) 22- ( - x ) = 12
-x = 22 - 12
-x = 10
x = -10
i) ( x + 5 ) + ( x - 9 ) = x + 2
x + 5 + x - 9 = x + 2
x + x + ( 5 - 9 ) = x + 2
x + x + ( -4 ) = x + 2
x + x = x + 2 - ( -4 )
x + x = x + 2 + 4
x + x =x + 6
=> x = 6
bài 1 :
a) S1=( 1 + 3 - 5 - 7 )+(9+11-13-15)+...+(393+395-397-399)
S1=(-8)+(-8)+...+(-8)
S1=(-8)*199
S1=-1592
b)S2=(1-2-3+4)+( 5 - 6 - 7 +8)+...+( 97 - 98 - 99 + 100)
S2=0+0+...+0
S2=0*100
S2=0
phần c và d tương tự nhé
BÀI 2
c)<=>2(x-1)+4 chia hết x-3
=>8 chia hết x-3
=>x-3\(\in\){-1,-2,-4,-8,1,2,4,8}
=>x\(\in\){2,1,-1,-5,4,5,7,11}
\(1.D,\:\:\:2.D,\:\:\:3.B,\:\:\:4.C,\:\:\:5.D,\:\:\:6.B,\:\:\:\:7.D\)