a(x - y) - b(y - x)² is equal to:

1. (x - y)(a - by + bx)

2. (y - x)(a - bx + by)

3. (x - y) (a - bx - by)

4. (x - y) (a - bx + by)

Factorise :

17a⁶b⁸ - 34a⁴b⁶ + 51a²b⁴

Factorise :

x²(a - b) - y²(a - b) + z²(a - b)

Factorise :

(x + y)(a + b) + (x - y)(a + b)