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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 5:
a) Phương trình hoành độ giao điểm của (d1) và (d2) là:
\(2x+1=-x+3\)
\(\Leftrightarrow2x+x=3-1\)
\(\Leftrightarrow3x=2\)
hay \(x=\dfrac{2}{3}\)
Thay \(x=\dfrac{2}{3}\) vào (d1), ta được:
\(y=2\cdot\dfrac{2}{3}+1=\dfrac{4}{3}+1=\dfrac{7}{3}\)
2) Thay \(x=\dfrac{2}{3}\) và \(y=\dfrac{7}{3}\) vào (d3), ta được:
\(\left(m-1\right)\cdot\dfrac{2}{3}+3m-2=\dfrac{7}{3}\)
\(\Leftrightarrow\dfrac{2}{3}m-\dfrac{2}{3}+3m-2=\dfrac{7}{3}\)
\(\Leftrightarrow m\cdot\dfrac{11}{3}=5\)
hay \(m=\dfrac{15}{11}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
nói c1 với c2 ta có đoạn o1o2
-vẽ đường trung trục của o1o2 .và đườn đó là MN như hình vẽ
-phép đôí xứng trục qua MN sẽ biến (c1) thành (c2).như vậy ta có đc đpcm
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 5:
1. There are a few students taking part in the event
→ There aren't many students taking part in the event.
2. If he doesn't work hard, he will lose his job
→ Unless he works hard, he will lose his job.
3. Let's write about the three Rs ?
→ Why don't we write about the three Rs?
4. Learning about recyking is fun
→ It's fun to learn about recycling.
5. It's not good to throw old clothes away
→ You shouldn't throw old clothes away
Xếp từ thành câu
Bài 1
1. they / to / movies / do / how / go / the / often ?
→ How often do they go to the movies?
2. your eyes / swimming / should / when goggles / you / you / go / wear / to protect
→ When you go swimming, you should wear goggles to protect your eyes.
3. usually / his / swimming / with / friends / he / goes
→ He usually goes swimming with his friends.
4. go / do / weekend / on / always / fishing / parents / their ?
→ Do their parents always go fishing on the weekend?
5. camping / they / go / do / sometimes
→ Sometimes they go camping.
6. what / TV / you / do / on / sports / watch?
→ What sports do you watch on TV?
Bài 2
1. Our / important / an / sports and games / in play / lives / part
→ Sports and games play an important part in our lives.
2. players / how / match / there / in / many / are / football / a ?
→ How many players are there in a football match?
3. by / she / to keep / every day / tries / fit / jogging
→ She tries to keep fit by jogging every day.
4. yesterday / who / play / football / you / did / with ?
→ Who did you play football with yesterday?
5. sports / building / physical and strength / necessary / are / for
→ Sports are necessary for building physical strength.
6. to switch / before / go / don't / the TV / off / you / forget / to bed
→ Don't forget to switch off the TV before you go to bed.
7. Sunday / I / usually / friends / swimming / on / go / mornings / with / my
→ On Sunday mornings, I usually go swimming with my friends.
8. match / you / on / the / did / television / last night / watch / basketball / the ?
→ Did you watch the basketball match on television last night?
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 2: Chọn C
Bài 4:
a: \(\widehat{C}=180^0-80^0-50^0=50^0\)
Xét ΔABC có \(\widehat{A}=\widehat{C}< \widehat{B}\)
nên BC=AB<AC
b: Xét ΔABC có AB<BC<AC
nên \(\widehat{C}< \widehat{A}< \widehat{B}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
3:
\(A=\dfrac{-1}{3}x^2y+\dfrac{2}{5}x^3-8xy-\dfrac{2}{3}x^2y-\dfrac{2}{5}x^3+xy-4-1\)
=-x^2y+7xy-5
Khi x=-1/3 và y=2 thì A=-1/9*2+7*(-1/3)*2-5
=-2/9-14/3-5
=-2/9-42/9-45/9
=-89/9
![](https://rs.olm.vn/images/avt/0.png?1311)
Đường tròn (C) có pt:
\(\left(x-2\right)^2+\left(y-1\right)^2=2\Rightarrow\) (C) tâm \(I\left(2;1\right)\) bán kính \(R=\sqrt{2}\)
\(\left(C_1\right)\) đối xứng (C) qua E \(\Rightarrow\left(C_1\right)\) có tâm \(I_1\) là ảnh của I qua phép đối xứng tâm I và bán kính \(R_1=R=\sqrt{2}\)
\(\left\{{}\begin{matrix}x_{I_1}=2x_E-x_I=0\\y_{I1}=2y_E-y_I=3\end{matrix}\right.\)
Phương trình: \(x^2+\left(y-3\right)^2=2\)
Bài 3 : Để ptđt (d2) là pt bậc nhất khi \(m\ne0\)
a, Hoành độ giao điểm thỏa mãn phương trình
\(x+1=mx+3m\Leftrightarrow x-mx=3m-1\Leftrightarrow x\left(1-m\right)=3m-1\)
\(\Leftrightarrow x=\frac{3m-1}{1-m}\)
\(\Rightarrow y=x+1=\frac{3m-1}{1-m}+1=\frac{3m-1+1-m}{1-m}=\frac{2m}{1-m}\)
b, Thay x = 0 vào ptđt (d1) ta được : \(y=1\)
Vậy (d1) cắt (d2) tại A(0;1)
Với \(m\ne0\)ta có :
Thay x = 0 ; y = 1 vào ptđt (d2) ta được : \(1=3m\Leftrightarrow m=\frac{1}{3}\)( tm )
3, Thay y = 0 vào ptđt (d1) ta được : \(x=-1\)
Vậy (d1) cắt (d2) tại B(-1;0)
Với \(m\ne0\)ta có :
Thay x = -1 ; y = 0 vào ptđt (d2) ta được : \(-m+3m=0\Leftrightarrow m=0\)
4, Thay \(x=\frac{3m-1}{1-m};y=\frac{2m}{1-m}\)vào ptđt (d3) ta được :
\(y=x+1\Rightarrow\frac{2m}{1-m}=\frac{3m-1}{1-m}+1\)ĐK : \(m\ne0;1\)
\(\Rightarrow2m=3m-1+1-m\Leftrightarrow2m=2m\)* đúng *
Vậy giao điểm (d1) và (d2) thuộc (d3)