а) (2x+5)(4+3x) = 2x 4 + 2x 3x + 5 4 + 5 3x= 8x + 6x^2 + 20 + 15x= 6x^2 + 23x + 20
б) (1-a)(5a+6) = 1 5a + 1 6 - a 5a - a 6= 5a + 6 - 5a^2 - 6a= -5a^2 - a + 6
в) (2x-y)(3y-4x) = 2x 3y - 2x 4x - y 3y + y 4x= 6xy - 8x^2 - 3y^2 + 4xy= -8x^2 + 10xy - 3y^2
а) (2x+5)(4+3x) = 2x 4 + 2x 3x + 5 4 + 5 3x
= 8x + 6x^2 + 20 + 15x
= 6x^2 + 23x + 20
б) (1-a)(5a+6) = 1 5a + 1 6 - a 5a - a 6
= 5a + 6 - 5a^2 - 6a
= -5a^2 - a + 6
в) (2x-y)(3y-4x) = 2x 3y - 2x 4x - y 3y + y 4x
= 6xy - 8x^2 - 3y^2 + 4xy
= -8x^2 + 10xy - 3y^2