Ta có:

\(x_1^2+x_2^2=5\Leftrightarrow\left(x_1+x_2\right)^2-2x_1x_2\)(1)

Áp dụng định lý Viet ta có :\(\left\{{}\begin{matrix}x_1+x_2=-\dfrac{b}{a}=\dfrac{2\left(m+1\right)}{1}=2m+1\\x_1x_2=\dfrac{c}{a}=\dfrac{m^2+2}{1}=m^2+2\end{matrix}\right.\)=> Thay vào (1) ta có :

\(\left(1\right)\Leftrightarrow\left(2m+1\right)^2-2\left(m^2+2\right)=5\)

\(\Leftrightarrow4m^2+4m+1-2m^2-4=5\)

\(\Leftrightarrow2m^2+4m=8\Leftrightarrow m^2-2m+1=9\)

\(\Leftrightarrow\left(m-1\right)^2=9\Leftrightarrow\left[{}\begin{matrix}m-1=3\\m-1=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}m=4\\m=-2\end{matrix}\right.\)

Phép lai đã giúp Coren phát hiện ra sự di truyền qua tế bào chất là:

A. Lai tế bào.

B. Lai thuận nghịch.

C. Lai cận huyết.

D. Lai phân tích.

số đó là 980 đây ~!

1)has already given

2)got

3/-Liz didn't enjoy her summer vacation last year.

-Did Liz enjoy her summer vacation last year?

4/-Nam won't be absent from school tomorrow.

-Will Nam be absent from school tomorrow?

Could you tell me the way to go to the bark?

khong theo 1 cong thuc nao ca

1/ I went swimming yesterday.

2/ Mrs.Nhung washed the dishes.

3/My mother went shopping with her friends in the park.

4/ Lan cooked the chicken noodle for the dinner.

5/Nam and I studied hard last weekend.

6/My father played golf yesterday.

7/Last night, Phong listened to music for two hours.

8/They had a nice yesterday.