1. B

2. B

3. C

4. C

5. B

6. B

7. D

8. C

9. C

10. A

\(A=\dfrac{x^2+8x+16-x^2}{2\left(x+2\right)}=\dfrac{8x+16}{2\left(x+2\right)}=\dfrac{8\left(x+2\right)}{2\left(x+2\right)}=4\)

=> biểu thức không phụ thuộc vào x

a) \(x^2+2x7+49-x^2+3x=12\Leftrightarrow17x=-37\Leftrightarrow x=\dfrac{-37}{17}\)

b) \(x^2-2x-x+2=0\Leftrightarrow x\left(x-2\right)-\left(x-2\right)=0\Leftrightarrow\left(x-1\right)\left(x-2\right)=\left(0\right)\Leftrightarrow x=1,x=2\)