giups mk bài toán nha
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NT
1
20 tháng 7 2017
Vẽ Oz // Ax
=> \(\widehat{xAO}=\widehat{AOz}\left(soletrong\right)=50^0\)
Ta có: \(\widehat{AOz}+\widehat{zOB}=\widehat{AOB}\)
hay \(50^0+\widehat{zOB}=80^0\)
\(\widehat{zOB}=80^0-50^0\)
=> \(\widehat{zOB}=30^0\)
Vì Ax // Oz
mà Ax // By
=> Oz // By
=> \(\widehat{OBy}=\widehat{zOB}\left(soletrong\right)=30^0\)
=> \(\widehat{OBy}=30^0\)
TV
3
S
14 tháng 12 2016
a) 6,21 : 4,5 + 31,5 : 4,5 - 7,74 : 4,5
= (6,21 + 31,5 - 7,74) : 4,5
= 29,97 : 4,5
= 6,66
10 tháng 3 2017
Chuyển các câu sau sang bị động
1.My father waters this flower every morning.
==> This flower is watered (by my father) every morning.
2.John invited Fiona to his birthday party last night.
==> Fiona was invented to John’s birthday party last month.
3.Her mother is preparing the dinner in the kitchen.
==> The dinner is being prepared (by her mother) in the kitchen.
4.We should clean our teeth twice a day.
==> Our teeth should be cleaned twice a day.
5.Our teachers have explained the English grammar.
==> The English grammar has been explained (by our teacher).
6.Some drunk drivers caused the accident in this city.
==> The accident was caused in this city (by some drunk drivers).
7.Tom will visit his parents next month.
==> Tom’s parents will be visited (by him) next month.
8.The manager didn’t phone the secretary this morning.
==> The secretary wasn’t phoned (by the manager) this morning.
9.Did Mary this beautiful dress?
==> Was this beautiful dress bought by Mary?
10.I won’t hang these old pictures in the living room.
==> These old pictures won’t be hung in the living room(by me).
11.The German didn’t build this factory during the Second World War.
==> This factory wasn’t built (by the Greens) during the Second World War.
12.The Greens are going to paint this house and these cars for Christmas Day.
==> This house and these cars are going to be painted for Christmas day by the Greens.
13. Ann had fed the cats before she went to the cinema.
==> The cats had been fed (by Ann) before she went to the cinema.
14.The students have discussed the pollution problems since last week.
==> The pollution problems have been discussed (by the students) since last week.
15.Have the thieves stolen the most valuable painting in the national museum?
==> Has the most valuable painting in the national museum been stolen (by the thieves)?
16.Some people will interview the new president on TV.
==> The new president will be interviewed on TV (by some people).
17.How many languages do they speak in Canada?
==> How many languages are spoken in Canada(by them)?
18.Are you going to repair those shoes?
==> Are those shoes going to be repaired ?
19.He has broken his nose in a football match.
==> His nose has been broken in a football match(by him).
20.Have you finished the above sentences?
==> Have above sentences been finished ?
Chúc pạn hok tốt!!!
TN
3
Bài 3.2:
a: ta có: |x+9|=2x
\(\Leftrightarrow\left\{{}\begin{matrix}x>=0\\\left(2x\right)^2-\left(x+9\right)^2=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ge0\\\left(2x-x-9\right)\left(2x+x+9\right)=0\end{matrix}\right.\)
=>x=9
b: ta có: \(\left|5x\right|=3x-2\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>=\dfrac{2}{3}\\\left(5x-3x+2\right)\left(5x+3x-2\right)=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x>=\dfrac{2}{3}\\\left(2x+2\right)\left(8x-2\right)=0\end{matrix}\right.\)
hay \(x\in\varnothing\)
c: Ta có: \(\Leftrightarrow\left|x+6\right|=2x+9\)
\(\Leftrightarrow\left\{{}\begin{matrix}x\ge-\dfrac{9}{2}\\\left(2x+9-x-6\right)\left(2x+9+x+6\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x>=-\dfrac{9}{2}\\\left(x+3\right)\left(3x+15\right)=0\end{matrix}\right.\Leftrightarrow x=-3\)
d: \(\Leftrightarrow\left|2x-3\right|=21-x\)
\(\Leftrightarrow\left\{{}\begin{matrix}x< =21\\\left(21-x-2x+3\right)\left(21-x+2x-3\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x< =21\\\left(24-3x\right)\left(x+18\right)=0\end{matrix}\right.\Leftrightarrow x\in\left\{8;-18\right\}\)