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26 tháng 7 2023
1: AD=8-2=6cm
AD/AB=6/8=3/4
AE/AC=9/12=3/4
=>AD/AB=AE/AC
2: Xét ΔADE và ΔABC có
AD/AB=AE/AC
góc A chung
=>ΔADE đồng dạng với ΔABC
3: AI là phân giác
=>IB/IC=AB/AC
=>IB/IC=AD/AE
=>IB*AE=AD*IC
12 tháng 7 2023
1: \(=\dfrac{4\left(x-1\right)}{\left(x+1\right)^2}\cdot\dfrac{3\left(x+1\right)}{-20\left(x-1\right)}=\dfrac{-12}{20}\cdot\dfrac{1}{x+1}=\dfrac{-3}{5x+5}\)
2: \(=\dfrac{x^2-xy+y^2}{\left(x-y\right)\left(x+y\right)}\cdot\dfrac{\left(x-y\right)^2}{\left(x+y\right)\left(x^2-xy+y^2\right)}\)
\(=\dfrac{x-y}{\left(x+y\right)^2}\)
3: \(=\dfrac{1-4x^2-1}{1-2x}:\dfrac{4x^2-2x-4x^2}{2x-1}\)
\(=\dfrac{4x^2}{2x-1}\cdot\dfrac{2x-1}{-2x}\)
=-2x
22 tháng 7 2023
1: Sửa đề: Qua N kẻ đường song song với PC cắt AB tại F
Xét tứ giác CNFP có NF//PC
nên CNFP là hình thang
GH
12 tháng 7 2023
1
Với \(\left\{{}\begin{matrix}x\ne2\\x\ne-1\\x\ne\sqrt{\dfrac{1}{2}}\end{matrix}\right.\)
\(M=\left(\dfrac{x-1}{2-x}-\dfrac{x^2}{x^2-x-2}\right)\left(\dfrac{x^2+2x+1}{4x^4-4x^2+1}\right)\\ =\left(\dfrac{\left(x-1\right)\left(x+1\right)}{\left(2-x\right)\left(x+1\right)}+\dfrac{x^2}{\left(x+1\right)\left(2-x\right)}\right)\left(\dfrac{\left(x+1\right)^2}{\left(2x^2-1\right)^2}\right)\\ =\dfrac{x^2-1+x^2}{\left(x+1\right)\left(2-x\right)}\left(\dfrac{\left(x+1\right)^2}{\left(2x^2-1\right)^2}\right)\\ =\dfrac{\left(2x^2-1\right)\left(x+1\right)^2}{\left(x+1\right)\left(2-x\right)\left(2x^2-1\right)^2}\\ =\dfrac{x+1}{\left(2-x\right)\left(2x^2-1\right)}\)
2
Để M = 0 thì \(\dfrac{x+1}{\left(2-x\right)\left(2x^2-1\right)}=0\Rightarrow x+1=0\Rightarrow x=-1\) (loại)
Vậy không có giá trị x thỏa mãn M = 0
H9
HT.Phong (9A5)
CTVHS
12 tháng 7 2023
1) \(M=\left(\dfrac{x-1}{2-x}-\dfrac{x^2}{x^2-x-2}\right)\cdot\dfrac{x^2+2x+1}{4x^4-4x^2+1}\) (ĐK: \(\left\{{}\begin{matrix}x\ne2\\x\ne-1\\x\ne\sqrt{\dfrac{1}{2}}\end{matrix}\right.\))
\(M=\left(\dfrac{-\left(x-1\right)}{x-2}-\dfrac{x^2}{\left(x-2\right)\left(x+1\right)}\right)\cdot\dfrac{\left(x+1\right)^2}{\left(2x^2-1\right)^2}\)
\(M=\left(\dfrac{-\left(x-1\right)\left(x+1\right)}{\left(x-2\right)\left(x+1\right)}-\dfrac{x^2}{\left(x-2\right)\left(x+1\right)}\right)\cdot\dfrac{\left(x+1\right)^2}{\left(2x^2-1\right)^2}\)
\(M=\left(\dfrac{-\left(x^2-1\right)-x^2}{\left(x-2\right)\left(x+1\right)}\right)\cdot\dfrac{\left(x+1\right)^2}{\left(2x^2-1\right)^2}\)
\(M=\left(\dfrac{-x^2+1-x^2}{\left(x-2\right)\left(x+1\right)}\right)\cdot\dfrac{\left(x+1\right)^2}{\left(2x^2-1\right)^2}\)
\(M=\dfrac{-2x^2+1}{\left(x-2\right)\left(x+1\right)}\cdot\dfrac{\left(x+1\right)^2}{\left(2x^2-1\right)^2}\)
\(M=\dfrac{-\left(2x^2-1\right)\left(x+1\right)^2}{\left(x-2\right)\left(x+1\right)\left(2x^2-1\right)^2}\)
\(M=\dfrac{-\left(x+1\right)}{\left(x-2\right)\left(2x^2-1\right)}\)
2) Ta có: \(M=0\)
\(\Rightarrow\dfrac{-\left(x+1\right)}{\left(x-2\right)\left(2x^2-1\right)}=0\)
\(\Leftrightarrow-\left(x+1\right)=0\)
\(\Leftrightarrow-x=1\)
\(\Leftrightarrow x=-1\left(ktm\right)\)
P
2
H
2 tháng 7 2023
Bài `1`
\(a,A=a\left(a+b\right)-b\left(a+b\right)\\ =\left(a+b\right)\left(a-b\right)\)
Với `a=9;=10`
Ta có :
\(\left(a+b\right)\left(a-b\right)\\=\left(9+10\right)\left(9-10\right)\\ =19.\left(-1\right)\\ =-19\)
\(b,B=\left(3x+2\right)^2+\left(3x-2\right)^2-2\left(3x+2\right)\left(3x-2\right)\\ =\left(3x+2\right)^2-2\left(3x+2\right)\left(3x-2\right)+\left(3x-2\right)^2\\ =\left[\left(3x+2\right)-\left(3x-2\right)\right]^2\)
Với `x=-4`
Ta có :
\(\left[\left(3x+2\right)-\left(3x-2\right)\right]^2\\ =\left(3.4+2-3.4+2\right)^2\\ =\left(12+2-12+2\right)^2\\ =4^2\\ =16\)
\(2,\\ x^3-6x^2+9x\\ =x\left(x^2-6x+9\right)\\ =x\left(x-3\right)^2\\ x^2-2x-4y^2-4y\\ \)
`->` có đúng đề ko cậu
2 tháng 7 2023
2:
b; x^2-4y^2-2x-4y
=(x-2y)*(x+2y)-2(x+2y)
=(x+2y)(x-2y-2)
a: x^3-6x^2+9x
=x(x^2-6x+9)
=x(x-3)^2
DT
11 tháng 7 2023
a)
Bốn cảnh của bức tranh tứ bình đó: đêm vàng trên bờ suối có ánh trăng tan, trời mưa chuyển bốn phương ngàn, bình minh cây xanh nắng gội, chiều lênh láng máu sau rừng.
b)
Hai cảnh tượng đối lập tương phản của bài thơ:
- Cảnh "đêm vàng trên bờ suối có ánh trăng tan" và cảnh "bình minh cây xanh nắng gội".
Ý nghĩa của nó: tái hiện lại cuộc sống tự do thoải mái trong rừng của chúa tể sơn lâm, lúc say mồi lúc giấc ngủ tưng bừng.
GL
20 tháng 6 2023
1. Lan said she was working in Hanoi then
2. Binh said he needed a new bicycle
3. Mary said her English teacher was very humorous
4. My younger brother said he didn't want to stay at home then
5. Binh said Mr.Thanh could speak two languages well
6. Miss Hang said she would go on a picnic to Nha Trang the next day
7. Tom said he didn't know who she was
8. Mai told us that it was raining heavily outside
9. He said to his friend that he had to go home then
10. Hoa said she couldn't go out after 8 p.m
________
II
1. Lan asked Hoa if she could speak French well
2. I asked Mai if she was free that night
3. Nhi asked Mai if she liked listening to pop music
4. She asked me if she lived near there
5. A tourist asked me if I could tell her the way to the nearest post office
GL
16 tháng 6 2023
11. The tickets were too expensive for me to buy
12. That old house has just been sold
13. Minh told Ba to help him with his English speaking
14. The teacher said Trung not to make noise in class
15. Tom told Jerry to for him there
16. Nam asked Ha to buy her an English exercise book
17. Toan's father told him to get up early to learn his lesson
18. Nga's teacher said her to improve her English pronunciation
19. The doctor said Mr.Hoang to stay in bed for a few days
1. I'd rather you didn't ask me that question
2. I haven't seen Bob seen I was in HCM City
3. He would rather read books than watch TV
4. It took Peter three hours to repaint his house
5. He asked me if I knew to speak English
6. We haven't met each other for ten years
7. The film was so boring that she fell asleep
8. The furniture was too expensive for me to buy
9. The weather is so good that they are going for a picnic
10. The coffee is too hot for me to drink
thank bạn rất nhiều