842. 1) x(p - a) + y(a - p) - z(p - a) = x(p - a) - y(p - a) - z(p - a) =(x - y - z)(p - a)
2) m(n - 2) + p(n - 2) + (2 - n) = m(n - 2) + p(n - 2) - (n - 2) = (m + p - 1)(n - 2)
3) x(a + b + c) - y(a + b + c) + z(a + b + c) = (x - y + z)(a + b + c)
4) 2a(x + y - z) - 3b(x + y - z) - 5c(x + y - z) = (2a - 3b - 5c)(x + y - z)
843. 1) (a + b)³ - a(a + b)² = (a + b)²(a + b) - a(a + b)² = (a + b)²(a + b - a) =
b(a + b)²
2) (a² + b²)² - a²(a² + b²) = (a² + b²)(a² + b² - a²) = b²(a² + b²)
3) (a - b)³ + b(a - b)² = (a - b)²(a - b) + b(a - b)² = (a - b)²(a - b + a) = a(a - b)²
4) x + y - (x + y)² = (x + y) - (x + y)(x + y) = (x + y)(1 - x - y)