Приведу данные выражения к многочленам:
(5x+6)(2x-9)+4 = 10x^2 - 36x + 12x - 54 + 4 = 10x^2 - 24x - 50
(6x-7)(5x+2)-9 = 30x^2 + 12x - 35x - 14 - 9 = 30x^2 - 23x - 23
(9x+8)(2x-9)+4 = 18x^2 - 81x + 16x - 72 + 4 = 18x^2 - 65x - 68
(5x+6)(2x-9)+9 = 10x^2 - 45x + 12x - 54 + 9 = 10x^2 - 33x - 45
(6x-7)(5x-2)+8 = 30x^2 - 12x - 35x + 14 + 8 = 30x^2 - 47x + 22
(2x+8)(2x+9)+5 = 4x^2 + 9x + 16x + 72 + 5 = 4x^2 + 25x + 77
(2x+8)(3x+9)-5 = 6x^2 + 18x + 24x + 72 - 5 = 6x^2 + 42x + 67
(x^2 - 5x + 9)(5x^2 + 6x + 2) = 5x^4 + 6x^3 + 2x^2 -25x^3 - 30x^2 - 10x + 45x^2 + 54x + 18 = 5x^4 - 19x^3 + 17x^2 + 44x + 18
(x^2 - 5x + 9)(x^2 - 6x + 2) = x^4 - 6x^3 + 2x^2 - 5x^3 + 30x^2 - 10x + 9x^2 - 54x + 18 = x^4 - 11x^3 + 41x^2 - 64x + 18
(2a^2 + 6a + 1)(2a - 8a^2 - 3) = 4a^3 - 16a^4 - 6a^2 + 12a^2 - 48a^3 - 18a - 24a^2 + 96a^3 + 36a + 2a - 8 = -16a^4 + 44a^3 - 18a^2 + 38a - 8
(2a^2 + 6a + 1)(a - 5a^2 - 6) = 2a^3 - 10a^4 - 12a + 6a^3 - 30a^2 - 36 - a + 5a^2 + 6 = -10a^4 + 8a^3 - 25a^2 - 7a - 30
(2y + 6x)(8a - 6y) + 7 = 16ay - 12y^2 + 48ax - 36xy + 7
(2y + 6x)(3a - 8y) - 7 = 6ay - 16y^2 + 18ax - 48xy - 7
(2k + 6y)(5k - 8y) + 12k = 10k^2 - 16ky + 30ky - 48y^2 + 12k
(2k + 6y)(8k - 5y) - 12k = 16k^2 - 10ky + 48ky - 30y^2 - 12k
(-7x + 4y)(2x - 3y) + 13 = -14x^2 - 21xy + 8xy + 12y^2 + 13
(-7x + 4y)(9x - 2y) - 13 = -63x^2 + 14xy + 36xy - 8y^2 - 13
(8a - 3)(6x - 1) - 6x = 48ax - 8a - 18x + 3 - 6x = 48ax - 24x - 8a + 3
(8a - 3)(-6x - 5) + 6x = -48ax - 40a + 18x - 15 + 6x = -48ax + 24x - 40a - 15
(-9a - 3)(5x - 1) - 8x + 9a = -45ax + 9a - 15x + 3 - 8x + 9a = -45ax - 23x + 18a + 3
