trả lời câu của tui kìa

The students in this class were made ______very hard.

A. learning

B. having learnt

C. to learn

D. learn

1. were

2. are playing

3. Did...go

4. is cooking/ cooks

5. will..do ( hoặc là is...going to do )

6. bought

C(y) = 0 <=> \(y^2-4y+3\) = 0

=> \(y^2-2y-2y-2+5\)= 0

=> \(y\left(y-2\right)-2\left(y-2\right)+5=0\)

=> \(\left(y-2\right)^2+5=0\)

Ta có \(\left(y-2\right)^2\ge0\forall y\)

=> \(\left(y-2\right)^2+5\ge5>0\)

Vậy đa thức C(y) vô nghiệm

\(E\left(x\right)=0\) <=> \(x^2+x=0\)

=> \(x\left(x+1\right)=0\)

=> \(\left[{}\begin{matrix}x=0\\x+1=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)

Vậy E(x) có nghiệm là 0 hoặc -1