Factorise (i) 4p² - 9q² (ii) 63a² - 112b² (iii) 49x² - 36 (iv) 16x⁵ - 44x³ (v) (l+m)² - (l-m)² (vi) 9x²y² - 16 (vii) (x² - 6xy + y²) - z² (viii) 25a² - 8b² + 28bc - 49c²

(i) 4p² - 9q² = (2p)² - (3q)² = (2p + 3q)(2p - 3q)
(ii) 63a² - 112b² = 7[(3a)² - (4b)²] = 7(3a + 4b)(3a - 4b)
(iii) 49x² - 36 = [(7x)² - 6²] = (7x - 6)(7x + 6)
(iv) 16x⁵ - 44x³ = 4x³(4x² - 11)
(v) (l+m)² - (l-m)² = (l + m + l - m)(l + m - l + m) = 2l * 2m = 4lm
(vi) 9x²y² - 16 = [(3xy)² - 4²] = (3xy - 4)(3xy + 4)
(vii) (x² - 6xy + y²) - z² = [(x - y)² - z²] = (x - y + z)(x - y - z)
(viii) 25a² - 8b² + 28bc - 49c² = (5a)² - (2b - 7c)² = (5a + 2b - 7c)(5a - 2b + 7c)