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The teacher told everybody to shut up
Jane told Robert to open the window
She told him to phone his granny
She warned him not to be late
His mother told Micheal not to talk to the strangers
She told me not to listen to a work he says
Tony told Clare to help him clean up the kitchen
Alastair told Fiona to get out of his way
Dad told the boys to stay away from the dog when he was eating
Bob told Minne not to scratch the sofa
The teacher told Carlaf not to pick his nose in class
My father told me to look after my sister
The actor told Oliver to break a leg
refer
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1. "Don't play with these matches!"
→ My father warned me .not to play with those matches..
2. "I'm leaving here tomorrow."
→He said that ...he was leaving there the day after
3. "Perhaps we can go to Paris for the weekend."
→ He suggested going to Paris for the weekend
4. "My sister got married last year."
→ He told me that ....his sister had got married the year before
5. "What are you doing tomorrow?"
→ My friend ask me. what I was doing the day after
6. "Have you ever worker in London before?"
→ My boss wanted to know...if I had ever worked in London before
7. "We went out last night.“
→ My brothers said that ...they had gone out the night before
8. "I was waiting for the bus when he arrived."
→ He said to me that ...he was waiting for the bus when he had arrived
9. "Don't make a mess!"
→ My mother requested us not to make a mess
10. "You should stay in bed if you feel unwell."
→ The nurse advised me to stay in bed if I felt unwell
![](https://rs.olm.vn/images/avt/0.png?1311)
1. I got good mark once, but I don't have anymore
I used to have a good mark
2. His sister said, '' I don't buy this book''
His sister said that she đin't buy that book
3. They said, '' We have to try our best to win the match''
They told me they had to try them best to win the match
1, I got good mark once , but I don't have anymore .
\(\rightarrow\) I used to get good mark .
2, His sister said , '' I don't buy this book ''
\(\rightarrow\) His sister said that he didn't buy this book .
3, They said , '' We have to try our best to win the match ''
\(\rightarrow\) They told me that they had to try their best to win the match .
![](https://rs.olm.vn/images/avt/0.png?1311)
a: ΔOBC cân tại O
mà OA là đường cao
nên OA là phân giác của góc BOC
Xét ΔOBA và ΔOCA có
OB=OC
\(\widehat{BOA}=\widehat{COA}\)
OA chung
Do đó: ΔOBA=ΔOCA
=>\(\widehat{OBA}=\widehat{OCA}=90^0\)
=>AC là tiếp tuyến của (O)
b: Ta có: \(\widehat{KOA}+\widehat{BOA}=\widehat{KOB}=90^0\)
\(\widehat{KAO}+\widehat{COA}=90^0\)(ΔOCA vuông tại C)
mà \(\widehat{BOA}=\widehat{COA}\)
nên \(\widehat{KOA}=\widehat{KAO}\)
=>KA=KO
d: Xét (O) có
\(\widehat{ACI}\) là góc tạo bởi tiếp tuyến CA và dây cung CI
\(\widehat{CDI}\) là góc nội tiếp chắn cung CI
Do đó: \(\widehat{ACI}=\widehat{CDI}\)
ΔOCA vuông tại C
=>\(CO^2+CA^2=OA^2\)
=>\(CA^2=\left(2R\right)^2-R^2=3R^2\)
=>\(CA=R\sqrt{3}\)
Xét ΔACI và ΔADC có
\(\widehat{ACI}=\widehat{ADC}\)
\(\widehat{CAI}\) chung
Do đó: ΔACI đồng dạng với ΔADC
=>\(\dfrac{AC}{AI}=\dfrac{AD}{AC}\)
=>\(AI\cdot AD=AC^2=\left(R\sqrt{3}\right)^2=3R^2\) không đổi
![](https://rs.olm.vn/images/avt/0.png?1311)
Xét tg ABO và tg ACO có
AO chung
AB=AC (gt)
OB=OC=R
=> tg ABO = tg ACO (c.c.c)
\(\Rightarrow\widehat{ACO}=\widehat{ABO}=90^o\Rightarrow AC\perp OC\) => AC là tiếp tuyến với (O)
b/
Xét tg vuông EOI và tg vuông COI có
OE=OC=R; OI chung => tg EOI = tg COI (hai tg vuông có 2 cạnh góc vuông bằng nhau)
Xét tg vuông EDI và tg vuông CDI có
DI chung
tg EOI = tg COI (cmt) => IE=IC
=> tg EDI = tg CDI (hai tg vuông có 2 cạnh góc vuông bằng nhau)
Xét tg DEO và tg DCO có
DO chung
OE=OC=R
tg EDI = tg CDI (cmt) => DE=DC
=> tg DEO = tg DCO (c.c.c)
\(\Rightarrow\widehat{DEO}=\widehat{DCO}=90^o\Rightarrow DE\perp OE\) => DE là tiếp tuyến với (O, R)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
1 What is the largest group of 54 ethnic groups of VN?
2 Why is this dish called five-coloured sticky rice?
3 How many ethnic groups are there in VN?
4 Who wear a V-shaped front collar T-shirt?
5 Where do the Dao live mainly ?
![](https://rs.olm.vn/images/avt/0.png?1311)
`#3107.101107`
2.
a)
`(x - 2y)^2 = x^2 - 2*x*2y + (2y)^2 = x^2 - 4xy + 4y^2`
`=> -2xy -> -4xy`
b)
`(4a + 3b)^2 = (4a)^2 + 2*4a*3b + (3b)^2 = 16a^2 + 24ab + 9b^2`
`=>` `a^2 -> 16a^2`; `b^2 -> 9b^2`
c)
`9x^2 + 6xy + y^2 = (3x)^2 + 2*3x*y + y^2 = (3x + y)^2`
`=>` `(3x - y)^2 -> (3x + y)^2`
d)
`(a - 2b)^3 = a^3 - 3*a^2*2b + 3*a*(2b)^2 - (2b)^3 = a^3 - 6a^2b + 12ab^2 - 8b^3`
`=>` `-8a^2b -> -6a^2b`; `6ab^2 -> 12ab^2.`
Sử dụng các HĐT:
1) \(\left(A+B\right)^2=A^2+2AB+B^2\)
2) \(\left(A-B\right)^2=A^2-2AB+B^2\)
3) \(\left(A-B\right)^3=A^3-3A^2B+3AB^2-B^3\)
Làm bài này bạn chú ý cả 2 vế xem có phân tích được ra HĐT hoặc chỉnh ntnao cho đúng vs HĐT nha :v.