giải hộ em câu này với
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: Xét tứ giác OBAC có
\(\widehat{OBA}+\widehat{OCA}=180^0\)
Do đó: OBAC là tứ giác nội tiếp
![](https://rs.olm.vn/images/avt/0.png?1311)
a: Ta có: \(P=A\cdot B\)
\(=\dfrac{\sqrt{x}-1}{\sqrt{x}+1}\cdot\dfrac{\sqrt{x}+6}{\sqrt{x}-1}\)
\(=\dfrac{\sqrt{x}+6}{\sqrt{x}+1}\)
Để P nguyên thì \(\sqrt{x}+1\in\left\{1;5\right\}\)
\(\Leftrightarrow\sqrt{x}\in\left\{0;4\right\}\)
hay \(x\in\left\{0;16\right\}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
e) \(15,6\times7,5+15,6\times2,5\)
\(\Rightarrow15,6\times\left(7,5+2,5\right)\)
\(\Rightarrow15,6\times10\)
\(\Rightarrow156\)
![](https://rs.olm.vn/images/avt/0.png?1311)
B, Đồ thị y thì nhìn vào dáng điệu, đồ thị y' thì chú ý trục hoành
![](https://rs.olm.vn/images/avt/0.png?1311)
1 Mary asked me who I talked to when i had problems
2 Hoa said she would help her mum cook dinner that night
3 jack advised me to tell my teacher what had happened
4 Nam said his best friend hadn't called him for one week
5 Lucia's mother asked her if she was at the sports center then
6 Tom asked mark what time he had come home the night before
7 Mrs Brown told me not to go to the park when it gets dark
8 Mrs QUang told Trung they had spoken to his parents the day before
9 Minh asked Phuong if he could meet her at 4.30 the day after afternoom
10 Nga said she was staying with her aunt and uncle in the suburbs
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(\text{Δ}=1-4m\)
Để phương trình vô nghiệm thì -4m+1<0
=>m>1/4
Để phương trình có nghiệm kép thì -4m+1=0
hay m=1/4
Để phương trình có vô số nghiệm thì -4m+1>0
hay m<1/4
b: \(\text{Δ}=9-4\cdot1\cdot\left(-m\right)=4m+9\)
Để phương trình vô nghiệm thì 4m+9<0
hay m<-9/4
Để phương trình có nghiệm kép thì 4m+9=0
hay m=-9/4
Để phương trình có 2 nghiệm phân biệt thì 4m+9>0
hay m>-9/4
![](https://rs.olm.vn/images/avt/0.png?1311)
\(b,\Leftrightarrow\left\{{}\begin{matrix}m+2=1\\m\ne2\end{matrix}\right.\Leftrightarrow m=-1\\ c,\text{PT giao Ox: }y=0\Leftrightarrow\left(m+2\right)x-m=0\\ \text{Thay }x=2\Leftrightarrow2m+4-m=0\\ \Leftrightarrow m=-4\\ d,\text{PT giao Ox và Oy: }\\ y=0\Leftrightarrow x=\dfrac{m}{m+2}\Leftrightarrow A\left(\dfrac{m}{m+2};0\right)\Leftrightarrow OA=\left|\dfrac{m}{m+2}\right|\\ x=0\Leftrightarrow y=-m\Leftrightarrow B\left(0;-m\right)\Leftrightarrow OB=\left|m\right|\\ \Delta OAB\text{ cân }\Leftrightarrow OA=OB\Leftrightarrow\left|\dfrac{m}{m+2}\right|=\left|m\right|\\ \Leftrightarrow\left[{}\begin{matrix}\dfrac{m}{m+2}=m\\\dfrac{m}{m+2}=-m\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}m\left(m+1\right)=0\\m\left(m+3\right)=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}m=0\\m=-1\\m=-3\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: Ta có: \(x^2-x+1\)
\(=x^2-2\cdot x\cdot\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{3}{4}\)
\(=\left(x-\dfrac{1}{2}\right)^2+\dfrac{3}{4}\ge\dfrac{3}{4}\forall x\)
Dấu '=' xảy ra khi \(x=\dfrac{1}{2}\)
d: Ta có: \(x^2-2x+\left|y+1\right|+5\)
\(=\left(x-1\right)^2+\left|y+1\right|+4\ge4\forall x,y\)
Dấu '=' xảy ra khi x=1 và y=-1
câu mấy vậy em