Our teacher tells us not to throw trarsh on the street.

My parents sometimes watch films on TV at night.

The Great Wall of China is a wonder of the world.

John comes from Washington D.C.

We put all our books on the bookshelf.

I usually go to school at half past six.

1. There are four people in Nam's family?

2. They are in the living room now.

Something like that feasible?

As well as the lemon juice.

Thế 5xy = 2x + 3y vào phương trình thứ 2 

=> 4x² + y² = y. (2x + 3y)

<=> 4x² + y² = 2xy + 3y²

<=>  4x² - 2y² -  2xy = 0

<=> 2x² - y² - xy = 0 

<=> (x² - y²) + (x² - xy) = 0 <=> (x - y)(x + y) + x(x - y) = 0

<=> (x - y).(2x + y) = 0

<=> x = y hoặc y = -2x

+) TH1: x = y. thay vào PT thứ nhất trong hệ => 2x + 3x = 5x² <=> 5x - 5x² = 0 <=> 5x(1-x) = 0

<=> x = 0 hoặc x = 1

Vậy x= y = 0 hoặc x = y = 1

+) TH2: y = - 2x => 2x + 3.(-2x) = 5x.(-2x)

<=> -4x = -10x² <=> 4x - 10x² = 0 <=> x(4 - 10x) = 0 <=> x = 0 hoặc x = 2/5

Vậy x= 0; y = 0 hoặc x = 2/5; y = -4/5

Nghiệm của hệ đã cho là: (x;y) = (0;0); (1;1); (2/5; -4/5)