7(x + 3y)² - 2x - 6y in the form of factors is :

1. (9x² + 21xy)(x + 6y)

2. 9(x + 3y)(x + 3y - 1)

3. (x + 3y)(7x + 21y - 2)

4. 7(x + 3y)(x + 3y - 3)

8(x - y) + 5(y - x) in the form of factors is :

1. 3(x + y)

2. 13(x - y)

3. 3(x - y)

4. 13(x + y)

3ab - 6b + 4a² - 8a in the form of factors is :

1. (a + 2)(4a + 3b)

2. (a - 2)(4a + 3b)

3. (a - 2)(4a - 3b)

4. (a + 2)(4a - 3b)

Factorise by taking out the common factors :

xy(3x² - 2y²) - yz(2y² - 3x²) + zx(15x² - 10y²)