Question

Tìm x

a) | 2x - 1| = | - 7|

b) | x + 5| = 0

c) 8x - 75 = 5x + 21

d) 9x + 25 = - (2x-58)

Answer 1

a) |2x-1|=|-7|

<=>|2x-1|=7

<=>\(\left[\begin{matrix}2x-1=7\\-\left(2x-1\right)=7\end{matrix}\right.\)

<=>\(\left[\begin{matrix}x=4\\x=-3\end{matrix}\right.\)

Vậy: x=-3 hoặc x=4

Answer 2

b) |x+5|=0

<=>x+5=0

<=>x=-5

Vậy: x=-5

Answer 3

c) 8x-75=5x+21

<=>8x-5x=21+75

<=>3x=96

<=>x=32

Vậy: x=32

Answer 4

d)9x+25=-(2x-58)

<=>9x+25=-2x+58

<=>9x+2x=58-25

<=>11x=33

<=>x=3

Vậy: x=3

Answer 5

a. \(\left|2x-1\right|=\left|-7\right|\)

\(\Rightarrow\left|2x-1\right|=7\)

\(\Rightarrow2x-1=7\) hoặc \(2x-1=-7\)

+) Nếu \(2x-1=7\)

\(\Rightarrow2x=8\)

\(\Rightarrow x=4\)

+) Nếu \(2x-1=-7\)

\(\Rightarrow2x=-6\)

\(\Rightarrow x=-6:2\)

\(\Rightarrow x=-3\)

Vậy \(x=4;x=-3\)

b. \(\left|x+5\right|=0\)

\(\Rightarrow x+5=0\)

\(\Rightarrow x=-5\)

c. \(8x-75=5x+21\)

\(\Rightarrow8x-5x=21+75\)

\(\Rightarrow3x=96\)

\(\Rightarrow x=96:3\)

\(\Rightarrow x=32\)

d. \(9x+25=-\left(2x-58\right)\)

\(\Rightarrow9x+25=-2x+58\)

\(\Rightarrow9x+2x=58-25\)

\(\Rightarrow11x=33\)

\(\Rightarrow x=3\)

Answer 6

a) 4 hoặc -6

b)-5

c)3x=-54.x=-18

|

Answer 7

a)\(\left|2x-1\right|\)=7

2x-1=7

2x=8

x=4

vay x=4

b)x+5=0

x=-5

vay x=-5

c)75=8x-5x+21

75=x(8-5)+21

75=x.3+21

75-21=x.3

54=x.3

28=x

vay x=28

d)9x+25=-2x+58

9x+2x=58-25

11x=33

x=3

vay x=3

Answer 8

a) \(\left|2x-1\right|=\left|-7\right|\)

\(\left|2x-1\right|=7\)

\(\Rightarrow\left[\begin{matrix}2x-1=7\\2x-1=-7\end{matrix}\right.\)

\(\Rightarrow\left[\begin{matrix}2x=7+1\\2x=-7+1\end{matrix}\right.\)

\(\Rightarrow\left[\begin{matrix}2x=8\\2x=-6\end{matrix}\right.\)

\(\Rightarrow\left[\begin{matrix}x=8:2\\x=-6:2\end{matrix}\right.\)

\(\Rightarrow\left[\begin{matrix}x=4\\x=-3\end{matrix}\right.\)

b)\(\left|x+5\right|=0\)

\(x=0-5\)

\(x=-5\)