1: Tọa độ điểm G là:

\(\left\{{}\begin{matrix}x_G=\dfrac{1+4+\left(-2\right)}{3}=\dfrac{3}{3}=1\\y_G=\dfrac{6-3+3}{3}=2\end{matrix}\right.\)

1: Tọa độ điểm G là:

\(\left\{{}\begin{matrix}x_G=\dfrac{1+4+\left(-2\right)}{3}=1\\y_G=\dfrac{6-3+3}{3}=2\end{matrix}\right.\)

ĐKXĐ: \(x\le4\)

\(\Leftrightarrow\left(x^3+3x^2+3x+1\right)+6\left(x+1\right)-\left(4-x\right)\sqrt{4-x}-6\sqrt{4-x}=0\)

\(\Leftrightarrow\left(x+1\right)^3+6\left(x+1\right)-\left(\sqrt{4-x}\right)^3-6\sqrt{4-x}=0\)

Đặt \(\left\{{}\begin{matrix}x+1=a\\\sqrt{4-x}=b\ge0\end{matrix}\right.\)

\(\Rightarrow a^3+6a-b^3-6b=0\)

\(\Rightarrow\left(a-b\right)\left(a^2+ab+b^2\right)+6\left(a-b\right)=0\)

\(\Rightarrow\left(a-b\right)\left[\left(a+\dfrac{b}{2}\right)^2+\dfrac{3b^2}{4}+6\right]=0\)

\(\Rightarrow a=b\)

\(\Rightarrow\sqrt{4-x}=x+1\left(x\ge-1\right)\)

\(\Rightarrow4-x=x^2+2x+1\)

\(\Rightarrow x^2+3x-3=0\Rightarrow\left[{}\begin{matrix}x=\dfrac{-3+\sqrt{21}}{2}\\x=\dfrac{-3-\sqrt{21}}{2}< -1\left(loại\right)\end{matrix}\right.\)

\(c,x\left(x-20\right)-x+20=0\\ \Leftrightarrow x^2-20x-x+20=0\\ \Leftrightarrow x^2-21x+20=0\\ \Leftrightarrow\left(x-20\right)\left(x-1\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=20\\x=1\end{matrix}\right.\)

\(b,x^2-4+\left(x+2\right)\left(x-3\right)=0\\ \Leftrightarrow x^2-4+x^2-x-6=0\\ \Leftrightarrow2x^2-x-10=0\\ \Leftrightarrow\left(2x-5\right)\left(x+2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=-2\end{matrix}\right.\)

a: Ta có: \(x\left(x-20\right)-x+20=0\)

\(\Leftrightarrow\left(x-20\right)\left(x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=20\\x=1\end{matrix}\right.\)

b: Ta có: \(x^2-4+\left(x+2\right)\left(x-3\right)=0\)

\(\Leftrightarrow\left(x+2\right)\left(2x-5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=\dfrac{5}{2}\end{matrix}\right.\)

Lộn giúp em 4 câu gấp đc ko mn oi=_)

4D

D

1.D

2.B

1 D

2 B

B

7. các cô y tá// với vẻ buồn đến đưa đi và// ông ta //qua đời 

        CN                      VN                                 CN          VN

8.chọn A

8.A

\(\left(2+5+7\right)x=4\times7\)

\(14x=28\)

\(x=2\)

Trl :

2x + 5x + 7x = 2².7

14x = 4.7

14x = 28

x= 28 : 14

x = 2

Hok tốt