1. (4x-3y)^2-(2x+y)(3x-5y)
16x^2-24xy+9y^2-(6x^2-10xy+3xy-5y^2)
16x^2-24xy+9y^2-6x^2+10xy-3xy+5y^2
10x^2-17xy+14y^2
2.1. x y^2 (5 x - 2 y) (5 x + 2 y)
x y^2 (25 x^2 - 4 y^2)
y^2 (25 x^3 - 4 x y^2)
2.2. 5 (a - 3)^2
a (5 a - 30) + 45
5 (a^2 - 6 a + 9)
