1) (2x + 1)(5x - 4) = 10x^2 - 8x + 5x - 4 = 10x^2 - 3x - 4
2) (5a - 3b)(4a - b) = 20a^2 - 5ab - 12ab + 3b^2 = 20a^2 - 17ab + 3b^2
3) (3x + 2y)(x - y) = 3x^2 - 3xy + 2xy - 2y^2 = 3x^2 - xy - 2y^2
4) (p - 3q)(8p + 5q) = 8p^2 + 5pq - 24pq - 15q^2 = 8p^2 - 19pq - 15q^2
1) (2x + 1)(5x - 4) = 10x^2 - 8x + 5x - 4 = 10x^2 - 3x - 4
2) (5a - 3b)(4a - b) = 20a^2 - 5ab - 12ab + 3b^2 = 20a^2 - 17ab + 3b^2
3) (3x + 2y)(x - y) = 3x^2 - 3xy + 2xy - 2y^2 = 3x^2 - xy - 2y^2
4) (p - 3q)(8p + 5q) = 8p^2 + 5pq - 24pq - 15q^2 = 8p^2 - 19pq - 15q^2