Question

(2x+5y)(3x+4y)-(7x-3y)(2x+y)

Answer 1

$(2x + 5y)(3x + 4y) - (7x - 3y)(2x + y) \\ = (6x {}^{2} + 8xy + 15xy + 20y {}^{2}) - (14x {}^{2} + 7xy - 6xy - 3y {}^{2}) \\ = (6x {}^{2} + 23xy + 20y {}^{2}) - (14x {}^{2} + xy - 3y {}^{2}) \\ = 6x {}^{2} + 23xy + 20y {}^{2} - 14x {}^{2} - xy + 3y {}^{2} \\ = - 8x {}^{2} + 22xy + 23y {}^{2}$

Answer 2

$(6 {x}^{2} + 8xy + 15xy + 20 {y}^{2} ) - (14 {x}^{2} + 7xy - 6xy - 3 {y}^{2} ) \\ = 6 {x}^{2} + 8xy + 15xy + 20 {y}^{2} - 14 {x}^{2} - 7xy + 6xy + 3 {y}^{2} \\ = - 8 {x}^{2} + 23xy - xy + 23 {y}^{2} \\ = - 8 {x}^{2} + 22xy + 23 {y}^{2}$
hope this helps you...