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a. \(\left|x-3\right|-7=13\Leftrightarrow\left|x-3\right|=20\)
TH1: \(x-3=20\Leftrightarrow x=23\)
TH2: \(x-3=-20\Leftrightarrow x=-17\)
b. \(72-3.\left|x+1\right|=9\Leftrightarrow\left|x+1\right|=21\)
TH1: \(x+1=21\Leftrightarrow x=20\)
TH2: \(x+1=-21\Leftrightarrow x=-22\)
c. \(17-\left(43-\left|x\right|\right)=45\Leftrightarrow\left|x\right|=71\)
TH1: \(x=71\)
TH2: \(x=-71\)
d. \(3\left|x-1\right|-5=7\Leftrightarrow\left|x-1\right|=4\)
TH1: \(x-1=4\Leftrightarrow x=5\)
TH2: \(x-1=-4\Leftrightarrow x=-3\)
e. \(-12\left(x-5\right)+7\left(3-x\right)=5\Leftrightarrow-12x+60+21-7x=5\Leftrightarrow-19x=-76\Leftrightarrow x=4\)
a.
\(\left|x-3\right|-7=13\)
\(\left|x-3\right|=13+7\)
\(\left|x-3\right|=20\)
\(x-3=\pm20\)
- \(x-3=20\)
\(x=20+3\)
\(x=23\)
- \(x-3=-20\)
\(x=-20+3\)
\(x=-17\)
Vậy x = 23 hoặc x = - 17.
b.
\(72-3\times\left|x+1\right|=9\)
\(3\times\left|x+1\right|=72-9\)
\(3\times\left|x+1\right|=63\)
\(\left|x+1\right|=63\div3\)
\(\left|x+1\right|=21\)
\(x+1=\pm21\)
- \(x+1=21\)
\(x=21-1\)
\(x=20\)
- \(x+1=-21\)
\(x=-21-1\)
\(x=-22\)
Vậy x = 20 hoặc x = - 22.
c.
\(17-\left(43-\left|x\right|\right)=45\)
\(43-\left|x\right|=17-45\)
\(43-\left|x\right|=-28\)
\(\left|x\right|=43-\left(-28\right)\)
\(\left|x\right|=71\)
\(x=\pm71\)
Vậy x = 71 hoặc x = - 71.
d.
\(3\times\left|x-1\right|-5=7\)
\(3\times\left|x-1\right|=7+5\)
\(3\times\left|x-1\right|=12\)
\(\left|x-1\right|=12\div3\)
\(\left|x-1\right|=4\)
\(x-1=\pm4\)
- \(x-1=4\)
\(x=4+1\)
\(x=5\)
- \(x-1=-4\)
\(x=-4+1\)
\(x=-3\)
Vậy x = 5 hoặc x = - 3.
e.
\(-12\times\left(x-5\right)+7\times\left(3-x\right)=5\)
\(-12\times x+\left(-12\right)\times\left(-5\right)+7\times3-7\times x=5\)
\(-12\times x+60+21-7\times x=5\)
\(-19\times x+81=5\)
\(-19\times x=5-81\)
\(-19\times x=-76\)
\(x=\frac{-76}{-19}\)
\(x=4\)
Chúc bạn học tốt
a. 37-7.(x+1)=40-8.3
37 - 7(x+1) = 16
7(x+1) = 21
x+1 = 3
x=2
b. (x+5).3=11=10+(3+4).4
(sao có 2 dấu bằng, dấu nào là dấu cộng do viết nhầm ???)
c. 25-5.3+4.10=100-5.x
50 = 100 - 5x
5x = 50
x=10
d. 36+2.(x-7)=12+8.(3+5)-36
36 + 2(x-7) = 40
2(x-7) = 4
x-7 =2
x=9
e. 3.(x+7)-9=11.5-5-8
3(x+7) - 9 = 42
3(x+7) = 51
x+7 = 17
x=10
Bài 1:
a) \(\dfrac{9}{20}-\dfrac{8}{15}\times\dfrac{5}{12}\)
\(=\dfrac{9}{20}-\dfrac{2}{9}\)
\(=\dfrac{41}{180}\)
b) \(\dfrac{2}{3}\div\dfrac{4}{5}\div\dfrac{7}{12}\)
\(=\dfrac{2}{3}\times\dfrac{5}{4}\times\dfrac{12}{7}\)
\(=\dfrac{5}{6}\times\dfrac{12}{7}\)
\(=\dfrac{10}{7}\)
c) \(\dfrac{7}{9}\times\dfrac{1}{3}+\dfrac{7}{9}\times\dfrac{2}{3}\)
\(=\dfrac{7}{9}\times\left(\dfrac{1}{3}+\dfrac{2}{3}\right)\)
\(=\dfrac{7}{9}\times1\)
\(=\dfrac{7}{9}\)
Bài 2:
a) \(2\times\left(x-1\right)=4026\)
\(\left(x-1\right)=4026\div2\)
\(x-1=2013\)
\(x=2014\)
Vậy: \(x=2014\)
b) \(x\times3,7+6,3\times x=320\)
\(x\times\left(3,7+6,3\right)=320\)
\(x\times10=320\)
\(x=320\div10\)
\(x=32\)
Vậy: \(x=32\)
c) \(0,25\times3< 3< 1,02\)
\(\Leftrightarrow0,75< 3< 1,02\) ( S )
=> \(0,75< 1,02< 3\)
a) 3/8 . x = 9/8 - 1
3/8 . x = 1/8
x = 1/8 : 3/8
x = 1/3
b) 4/5 . x = 7/5 - 1/5
4/5 . x = 6/5
x = 6/5 : 4/5
x = 3/2
c) 12/7 : x + 2/3 = 7/5
12/7 : x = 7/5 - 2/3
12/7 : x = 11/15
x = 12/7 : 11/15
x = 180/77
d) 3.(x + 7) - 15 = 27
3.(x + 7) = 27 + 15
3.(x + 7) = 42
x + 7 = 42 : 3
x + 7 = 14
x = 14 - 7
x = 7
a) \(\dfrac{3}{8}x=\dfrac{9}{8}-1\)
\(\Rightarrow\dfrac{3}{8}x=\dfrac{1}{8}\)
\(\Rightarrow x=\dfrac{1}{8}:\dfrac{3}{8}=\dfrac{1}{3}\)
b) \(\dfrac{4}{5}x=\dfrac{7}{5}-\dfrac{1}{5}\)
\(\Rightarrow\dfrac{4}{5}x=\dfrac{6}{5}\)
\(\Rightarrow x=\dfrac{6}{5}:\dfrac{4}{5}=\dfrac{3}{2}\)
c) \(\dfrac{12}{7}:x+\dfrac{2}{3}=\dfrac{7}{5}\)
\(\Rightarrow\dfrac{12}{7}:x=\dfrac{7}{5}-\dfrac{2}{3}\)
\(\Rightarrow\dfrac{12}{7}:x=\dfrac{11}{15}\)
\(\Rightarrow x=\dfrac{12}{7}:\dfrac{11}{15}=\dfrac{180}{77}\)
d) \(3\left(x+7\right)-15=27\)
\(\Leftrightarrow3\left(x+7\right)=42\)
\(\Leftrightarrow x+7=14\Leftrightarrow x=7\)
b ) 3 - ( x - 5 ) = - 7 + ( - 8 )
3 - ( x - 5 ) = - 15
x - 5 = 3 - ( - 15 )
x - 5 = 18
x = 18 + 5
x = 23
Vậy x = 23