x/3=y/5 =>x=3/5 y

x^2-y^2=-4

<=>(x+y)(x-y)=-4

<=>(3/5 y+y)(3/5 y-y)=-4

<=>8/5.y.(-2/5).y=-4

<=>y^2=6,25

=>y=2,5 hoặc -2,5

=>x=1,5 hoặc -1,5

15x² + 7x - 2

= 15x² + 10x - 3x - 2

= 5x(3x + 2) - (3x + 2)

= (3x + 2)(5x - 1)

1. a large house in the countryside is

2. a set of rooms for living in, usually on one floor of a building is

3. a large and luxurious house with a large yard and garden

4. a terraced house in a city or town

5. a house built on piles above the ground or water