2,4 x Y = 6/5 x 0 b/ 5/4 : Y = 0,5
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a: \(\Leftrightarrow y\cdot2.4=\dfrac{6}{5}\cdot\dfrac{2}{5}=\dfrac{12}{25}\)
hay y=1/5
b: 5/4:y=1/2
nên y=5/4:1/2=5/2
![](https://rs.olm.vn/images/avt/0.png?1311)
1: Áp dụng tính chất của DTSBN, ta được:
\(\dfrac{x}{7}=\dfrac{y}{13}=\dfrac{x-y}{7-13}=\dfrac{42}{-6}=-7\)
=>x=-48; y=-91
2: x/y=3/4
=>4x=3y
=>4x-3y=0
mà 2x+y=10
nên x=3 và y=4
3: =>7x-3y=0 và x-y=-24
=>x=18 và y=42
4: =>7x-5y=0 và x+y=24
=>x=10 và y=14
![](https://rs.olm.vn/images/avt/0.png?1311)
dễ mà, tick nha
a)0,4:x=1,6-0,5:x
->0,4:x+0,5:x=1,6
->(0,4+0,5):x=1,6
->0,9:x=1,6
->x=0,9:1,6
->x=0,5625
Tick đi rồi mình giải típ câu b cho, đang bận
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\left|x-1\right|=5\)
\(\Rightarrow\orbr{\begin{cases}x-1=5\\x-1=-5\end{cases}}\)\(\Rightarrow\orbr{\begin{cases}x=6\\x=-4\end{cases}}\)
b) \(\left|x-0,5\right|=2,4\)
\(\Rightarrow\orbr{\begin{cases}x-0,5=2,4\\x-0,5=-2,4\end{cases}}\Rightarrow\orbr{\begin{cases}x=2,9\\x=-1,9\end{cases}}\)
c) \(2\left|3x-1\right|-1=6\)
\(\Leftrightarrow2\left|3x-1\right|=7\)
\(\Leftrightarrow\left|3x-1\right|=3,5\)
\(\Rightarrow\orbr{\begin{cases}3x-1=3,5\\3x-1=-3,5\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}3x=4,5\\2x=-2,5\end{cases}\Rightarrow\orbr{\begin{cases}x=1,5\\-1,25\end{cases}}}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, y \(\times\) \(\dfrac{4}{3}\) = \(\dfrac{16}{9}\)
y = \(\dfrac{16}{9}\) : \(\dfrac{4}{3}\)
y = \(\dfrac{4}{3}\)
b, ( y - \(\dfrac{1}{2}\)) + 0,5 = \(\dfrac{3}{4}\)
y - 0,5 + 0,5 = \(\dfrac{3}{4}\)
y = \(\dfrac{3}{4}\)
c, \(\dfrac{4}{5}-\dfrac{2}{5}y\) = 0,2
0,8 - 0,4y = 0,2
0,4y = 0,8 - 0,2
0,4y = 0,6
y = 1,5
d, (y + \(\dfrac{3}{4}\)) \(\times\) \(\dfrac{5}{7}\) = \(\dfrac{10}{9}\)
y + \(\dfrac{3}{4}\) = \(\dfrac{10}{9}\) : \(\dfrac{5}{7}\)
y + \(\dfrac{3}{4}\) = \(\dfrac{14}{9}\)
y = \(\dfrac{14}{9}\) - \(\dfrac{3}{4}\)
y = \(\dfrac{29}{36}\)
e, y : \(\dfrac{5}{4}\) = \(\dfrac{9}{5}\) + \(\dfrac{1}{2}\)
y : \(\dfrac{5}{4}\) = \(\dfrac{23}{10}\)
y = \(\dfrac{23}{10}\)
y = \(\dfrac{23}{8}\)
f, y \(\times\) \(\dfrac{1}{2}\) + \(\dfrac{3}{2}\) \(\times\) y = \(\dfrac{4}{5}\)
y \(\times\) ( \(\dfrac{1}{2}+\dfrac{3}{2}\)) = \(\dfrac{4}{5}\)
2y = \(\dfrac{4}{5}\)
y = \(\dfrac{2}{5}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
h/ Với mọi x, y ta có :
\(\left\{{}\begin{matrix}\left|x-0,5\right|\ge0\\\left|x+y-17\right|\ge0\end{matrix}\right.\)
\(\Leftrightarrow\left|x-0,5\right|+\left|x+y-17\right|\ge0\)
Dấu "=" xảy ra \(\Leftrightarrow\left\{{}\begin{matrix}\left|x-0,5\right|=0\\\left|x+y-17\right|=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x-0,5=0\\x+y-17=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=0,5\\y=16,5\end{matrix}\right.\)
Vaayj...
m/ \(\left(5-x\right)+\left(3x-\frac{1}{4}\right)>0\)
\(\Leftrightarrow5-x+3x-\frac{1}{4}>0\)
\(\Leftrightarrow2x-4,75>0\)
\(\Leftrightarrow x>2,375\)
Vậy...
q/ \(5^{3x-1}=625\)
\(\Leftrightarrow5^{3x-1}=5^4\)
\(\Leftrightarrow3x-1=4\Leftrightarrow x=\frac{5}{3}\)
Vậy..
![](https://rs.olm.vn/images/avt/0.png?1311)
a,\(\frac{-\chi}{4}=\frac{-9}{\chi}\Rightarrow-\chi.\chi=4.\left(-9\right)\)
\(\Rightarrow-2\chi=-36\Rightarrow\chi=-36:\left(-2\right)\)
\(\Rightarrow\chi=18\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(7,75-\left(0,5\times y\div5-6,2\right)=5\)
\(0,5\times y\div5-6,2=7,75-5=2,75\)
\(0,5\div5\times y-6,2=2,75\)
\(0,1\times y=2,75+6,2=8,95\)
\(\dfrac{1}{10}y=8,95\)
\(y=8,95\times10=89,5\)
\(y\div6\times7,2+1,3\times y+y\div2+15=19,95\)
\(1,2\times y+1,3\times y+0,5y=19,95-15=4,95\)
\(y\left(1,2+1,3+0,5\right)=4,95\)
\(2y=4,95\)
\(y=4,95\div2=2,475\)
\(a,2,4\times y=\frac{6}{5}\times0\\2,4\times y=0\\ y=0:2,4\\ y=0\\b,\frac{5}{4}:y=0,5\\ y=\frac{5}{4} :\frac{1}{2}\\ y=\frac{5}{2}\)
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