c)\(\Leftrightarrow x^2+x=x^2\Leftrightarrow x=1\)

b)\(\Leftrightarrow x^2-x-6=x-3\Leftrightarrow x^2-2x-3=0\Leftrightarrow\left(x-3\right)\left(x+1\right)\)

\(\Leftrightarrow\)\(\left[\begin{array}{nghiempt}x-3=0\\x+1=0\end{array}\right.\)\(\Leftrightarrow\)\(\left[\begin{array}{nghiempt}x=3\\x=-1\end{array}\right.\)

a)\(\Leftrightarrow x^2-x=3-x\)

\(\Leftrightarrow x^2=3\Leftrightarrow x=\pm\sqrt{3}\)

1 ) someone checks the water level every week.

the water level is checked every week

2 someone has  moved my chair.

my chair has been moved 

3 we had warned him not go near the river the day before .

he had been warned not to go near the river the day before by us

4 they were repairing the machine when the  accident happened.

the machine was being repaired when the accident happened by them

Bn tự vẽ hình nhé

Ta có OB=OA+AB =>AB=OB-OA=8-4=4 (cm)

Mà BC=AC+AB=6+4=10(cm)

\(=\frac{-3\cdot5}{7\cdot3^2}+\frac{2^2\cdot\left(-3\right)}{3^2\cdot7}+\frac{17}{7}=\frac{-5}{21}-\frac{4}{21}+\frac{17}{7}=\frac{-3}{7}+\frac{17}{7}=2\)

Tôi đã được học rằng bạn có thể tiếp tục lâu hơn bạn nghĩ bạn không thể

1 poor

2 elderly

3 sick

4 homeless

4 street

a)

ta có ABCD là hình bình hành nên :

góc A + góc B = 180 độ suy ra góc B = 180 độ - góc A = 180 - 110 = 70 độ

Mà góc D = góc B = 70 độ ; góc C = góc A = 110 độ