\(x^2-7=0\)

\(\Leftrightarrow x^2=7\)

\(\Leftrightarrow x=\pm\sqrt{7}\)

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Đọc và trả lời:

This is my father.His name is Nam. He is a worker.He gets up early at 5 a.m in the morning.He has breakfast at 5.30 a.m.His favourite food is noodles.He goes to work at 6 o'clock.He go to work from 8.00 a.m to 5.00 p.m.He goes to bed at 10 p.m.

1. What's his name?

His name is Nam.

2. What's his job?

He's a worker.

3. What time does he go to work?

He góe to work at 6 o'clock.

4.What's his favourite food?

His favourite food is noodles.

Ta có: \(\dfrac{a+b}{a-b}=\dfrac{c+d}{c-d}\Leftrightarrow\dfrac{a+b}{c+d}=\dfrac{a-b}{c-d}\)

\(\Leftrightarrow\dfrac{a}{c}=\dfrac{b}{d}\Leftrightarrow\dfrac{a}{b}=\dfrac{c}{d}\)