1) 13-(x-7)=5
<=> 13 - x + 7 = 5
<=> x = 15
2) /x/=2015 => x = 2015 hoặc x = -2015
3) 2x+17=15+x
<=> x = -2
4) 2x-9=-17
<=> 2x = -8
<=> x = -4
1) 13-(x-7)=5
<=>13-x+7=5
<=>20-x=5
<=>x=15
Vậy x=15
2) /x/=2015
<=> x= 2015 hoặc x=-2015
Vậy \(x\in\left\{\pm2015\right\}\)
3) 2x+17=15+x
<=>2x+17-15-x=0
<=>x+2=0
<=>x=-2
Vậy x=-2
4) 2x-9=-17
<=> 2x=-8
<=>x=-4
Vậy x=-4
tìm x biết
a) 13 - (x - 7) = 5
x - 7 = 13 - 5
x - 7 = 8
x = 8 + 7
x = 15
vậy x = 15
b) |x| = 2015
=> x = 2015; -2015
vậy x = 2015; -2015
d) 2x - 9 = -17
2x = -17 + 9
2x = -8
x = -8 : 2
x = -4
vậy x = -4
1) 13-(x-7)=5
x-7=8
x=8+7
x=15
2) /x/=2015
=> x=+2015
3) 2x+17=15+x
2x-x=15-17
x=-2
4) 2x-9=-17
2x=-17+9
2x=-8
x=-8:2
x=-4
\(1,13-\left(x-7\right)=5\)
<=> \(13-x+7=5\)
<=>\(-x=5-7-13\)
<=>\(-x=-15\)
<=>\(x=15\)
\(2,|x|=2015\)
<=>\(\orbr{\begin{cases}x=-2015\\x=2015\end{cases}}\)
\(3,2x+17=15+x\)
<=>\(2x-x=15-17\)
<=>\(x=-2\)
\(4,2x-9=-17\)
<=>\(2x=-8\)
<=>\(x=-4\)
Trả lời:
1) \(13-\left(x-7\right)=5\)
\(\Leftrightarrow x-7=13-5\)
\(\Leftrightarrow x-7=8\)
\(\Leftrightarrow x=8+7\)
\(\Rightarrow x=15\)
Vậy x= 15
2) \(\left|x\right|=2015\)
\(\Rightarrow\orbr{\begin{cases}x=2015\\x=-2015\end{cases}}\)
Vậy \(x\in\left\{2015;-2015\right\}\)
3) \(2x+17=15+x\)
\(\Leftrightarrow2x-x=15-17\)
\(\Leftrightarrow x=-2\)
4) \(2x-9=-17\)
\(\Rightarrow2x=-17+9\)
\(\Rightarrow2x=-8\)
\(\Rightarrow x=-8:2\)
\(\Rightarrow x=-4\)
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