Question

Answer 1

Câu 2. A

Giải thích:

Xét tập \(A=\left\{x\in R|2x^2-3x+1=0\right\}\)

Ta có: \(2x^2-3x+1=0\) có \(a+b+c=2+\left(-3\right)+1=0\Rightarrow\left[{}\begin{matrix}x=1\\x=\dfrac{1}{2}\end{matrix}\right.\).

\(\Rightarrow A=\left\{\dfrac{1}{2};1\right\}\).

Xét tập \(B=\left\{x\in N|3x+2< 10\right\}\)

Ta có: \(\left\{{}\begin{matrix}3x+2< 10\\x\in N\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x< \dfrac{8}{3}\\x\in N\end{matrix}\right.\Rightarrow x\in\left\{0;1;2\right\}\)

\(\Rightarrow B=\left\{0;1;2\right\}\)

\(\Rightarrow A\cup B=\left\{0;\dfrac{1}{2};1;2\right\}\)

Answer 2

3D

4B

5B

6A

7A