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a: =-3/4+1/2-1/13+3/13=-1/4+2/13=-13/52+8/52=-5/52
b: =10/11+1/11-1/8=1-1/8=7/8
c: =4(2,86+3,14)-30,05+9x0,75
=24-30,05+6,75
=0,7
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a: \(=\dfrac{1}{3}+\dfrac{1}{8}-\dfrac{3}{16}\cdot4=\dfrac{11}{24}-\dfrac{3}{64}=\dfrac{88}{192}-\dfrac{9}{192}=\dfrac{79}{192}\)
b: \(=\dfrac{5}{8}\cdot\left(-16\right)=-10\)
c: \(=\left(\dfrac{8}{5}+\dfrac{1}{3}\right):\dfrac{29}{5}-\dfrac{4}{81}\cdot9\)
\(=\dfrac{29}{15}\cdot\dfrac{5}{29}-\dfrac{4}{9}=\dfrac{1}{3}-\dfrac{4}{9}=-\dfrac{1}{9}\)
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\(c,=4\cdot\left(-\dfrac{1}{8}\right)-2\cdot\dfrac{1}{4}-\dfrac{3}{2}+1=-\dfrac{1}{2}-\dfrac{1}{2}-\dfrac{3}{2}+1=-\dfrac{3}{2}\\ \left(5x+\dfrac{2}{3}\right)^2=\dfrac{1}{4}\Rightarrow\left[{}\begin{matrix}5x+\dfrac{2}{3}=\dfrac{1}{2}\\5x+\dfrac{2}{3}=-\dfrac{1}{2}\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}5x=-\dfrac{1}{6}\\5x=-\dfrac{7}{6}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-\dfrac{1}{30}\\x=-\dfrac{7}{30}\end{matrix}\right.\\ c,x:2=\left(-4\right):5\Rightarrow x=-\dfrac{4}{5}\cdot2=-\dfrac{8}{5}\)
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B7 chu vi mảnh vườn là 3,3 m
diện tích là \(\dfrac{8}{7}\)m vuông
Bài 7:
Chu vi là:
\(\left(\dfrac{12}{5}+\dfrac{10}{21}\right)\cdot2=\dfrac{604}{105}\left(m\right)\)
Diện tích là:
\(\dfrac{12}{5}\cdot\dfrac{10}{21}=\dfrac{8}{7}\left(m^2\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
dễ mà bạn
a)3x-18=0 à mà mik chx hc phương trình
3x=18+0 sorry bạn nhé
3x=18
x=18:3
x=6
vậy x=6
a)\(3x-18=0\)
\(\Leftrightarrow3x=18\)
\(\Leftrightarrow x=6\)
Vậy x=6
b)\(2x.\left(x-4\right)-3x+12=0\)
\(\Leftrightarrow2x.\left(x-4\right)-3\left(x-4\right)=0\)
\(\Leftrightarrow\left(2x-3\right).\left(x-4\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}2x-3=0\\x-4=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=\frac{3}{2}\\x=4\end{cases}}}\)
Vậy .......
c)\(\frac{x-1}{2}-\frac{x+3}{3}=x+1\)
\(\Leftrightarrow6.\left(\frac{x-1}{2}-\frac{x+3}{3}\right)=6.\left(x+1\right)\)
\(\Leftrightarrow3.\left(x-1\right)-2.\left(x+3\right)=6x+6\)
\(\Leftrightarrow3x-3-2x-6=6x+6\)
\(\Leftrightarrow3x-2x-6x=6+3+6\)
\(\Leftrightarrow-5x=15\)
\(\Leftrightarrow x=-3\)
Vậy x= -3
d)\(\frac{x-3}{x+3}-\frac{5}{3-x}=\frac{30}{x^2-9}\)
\(\Leftrightarrow\frac{x-3}{x+3}-\frac{-5}{x-3}=\frac{30}{\left(x+3\right).\left(x-3\right)}\)
\(\Leftrightarrow\frac{\left(x-3\right).\left(x-3\right)}{\left(x+3\right).\left(x-3\right)}-\frac{-5.\left(x+3\right)}{\left(x-3\right).\left(x+3\right)}=\frac{30}{\left(x-3\right).\left(x+3\right)}\)
\(\Leftrightarrow\left(x-3\right)^2-\left(-5\right).\left(x+3\right)=30\)
\(\Leftrightarrow x^2-6x+9-\left(-5x-15\right)=30\)
\(\Leftrightarrow x^2-6x+9+5x+15-30=0\)
\(\Leftrightarrow x^2-x-6=0\)
\(\Leftrightarrow x^2-3x+2x-6=0\)
\(\Leftrightarrow x.\left(x-3\right)+2.\left(x-3\right)=0\)
\(\Leftrightarrow\left(x+2\right).\left(x-3\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x+2=0\\x-3=0\end{cases}\Leftrightarrow\orbr{\begin{cases}x=-2\\x=3\end{cases}}}\)
Vậy......
![](https://rs.olm.vn/images/avt/0.png?1311)
Tuy giàu nhưng cô ấy ăn uống rất đơn giản, không cần nem công chả phương
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4 has not been - broke
5 did you - was
6 have youy ever been
II
1 go
2 were
3 eats
7 does - won't worry
8 had played - would have won
9 will - do
10 were - would go
14 would have written
15 won't go
16 tries
17 spoke
19 finish - will go
20 see - ask
Rewrite
1 The man who doesn't work hard can't earn more money
3 If my friend and I had enough money, we would buy a house of our town
4 If the weather were better now, we could go for a walk
5 If I knew his addres, I would give it to you
6 If he worked slowly enough, he wouldn't make
7 If I were sent to proson, she would visit me
8 If I won a big prize in a lottery, I would give up my job
9 If the doctor weren't so late, he could see many patients
10 If tickets weren't expensive, we would visit them in Ha Noi
III
1 were
2 would visit
3 would give
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`4*5^2 -3^2 (2018^0 +3^2)`
`=4*25-9(1+9)`
`=100-9*10`
`=100-90`
`=10`