1)(a - x)²(x +a)² = (a - x)²(a + x)² = ((a - x)(a + x))² = (a² - x²)² = a⁴ - 2a²x² + x⁴

2) 9x² - (х - 1)² = (3х - х + 1)(3х + х - 1) = (2х + 1)(4х - 1) = 8х² +4х - 2х - 1 =

= 8х² + 2х - 1