Tim x biet (x:2+3)x6+7=25
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Ta có (7+x)/12=2/3
suy ra 3(7+x)=24
suy ra 7+x=8
x=1
Ta có (25-x)/18=1/2
suy ra 2(25-x)=18
suy ra 25-x=9
x=16
Tìm x thuoc z:
1) \(26-\left|x+9\right|=-13\)
\(\Leftrightarrow\left|x+9\right|=26-\left(-13\right)\)
\(\Leftrightarrow\left|x+9\right|=39\)
\(\Leftrightarrow\left[{}\begin{matrix}x+9=39\\x+9=-39\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=39-9=30\\x=-39-9=-48\end{matrix}\right.\)
Vậy: \(x\in\left\{30;-48\right\}\)
2) \(\left|x+7\right|-13=25\)
\(\Leftrightarrow\left|x+7\right|=25+13=38\)
\(\Leftrightarrow x+7\in\left\{38;-38\right\}\)
\(\Leftrightarrow x\in\left\{31;-45\right\}\)
Vậy:.................
tim x biet
\(1)123-3.\left(x+4\right)=23\)
\(\Leftrightarrow3\left(x+4\right)=123-23\)
\(\Leftrightarrow3\left(x+4\right)=100\)
\(\Leftrightarrow x+4=\frac{100}{3}\)
\(\Leftrightarrow x=\frac{100}{3}-4=\frac{100-12}{3}=\frac{88}{3}\)
Vậy:................
2) Tương tự
a, 1-[15+11] = x-[25-9]
1-16=x-16
-15=-x-16
x=-15+16
x=1
b,2-x=17-[-5]
2-x=17+5
2-x=22
x=2-22
x=-20
c, x-12=[-9]-15
x-12=-24
x=-24+12
x=-12
d,9-25=[ 7- x] -[25+7]
-16=[7-x]-32
[7-x]-32=-16
7-x=-16+32
7-x=16
x=7-16
x=-9
a)x-2/5=3/8
(x-2).8=5.3
x-2=5.3:8
x-2=1
=>x=3
b,c )tương tự
\(25\%x-\frac{7}{8}+x=\frac{2}{3}x\)
<=> \(\frac{1}{4}x-\frac{7}{8}+1x=\frac{2}{3}x\)
<=> \(\frac{1}{4}x+1x-\frac{2}{3}x=\frac{7}{8}\)
<=> \(x\left(\frac{1}{4}+1-\frac{2}{3}\right)=\frac{7}{8}\)
<=> \(x\cdot\frac{7}{12}=\frac{7}{8}\)
<=> \(x=\frac{12}{8}=\frac{3}{2}\)
Bài làm:
Ta có: \(25\%x-\frac{7}{8}+x=\frac{2}{3}x\)
\(\Leftrightarrow\frac{x}{4}+x-\frac{2}{3}x=\frac{7}{8}\)
\(\Leftrightarrow\frac{7}{12}x=\frac{7}{8}\)
\(\Leftrightarrow x=\frac{3}{2}\)