Verified answer

3) (2 - 3х)(5х - 3) - х(2 - х) = 3 - 12х²,

    10х - 6 - 15х² + 9х - 2х + х² - 3 + 12х² = 0,

    -2х² + 17х - 9 = 0,

    2х² - 17х + 9 = 0,

    a = 2, b = -17, c = 9;

4) (1 - 2x)(2x - 4) - 3(2 - x) = 3 - 9x²,

    2x - 4 - 4x² + 8x - 6 + 3x - 3 + 9x² = 0,

    5x² + 13x - 13 = 0,

    a = 5, b = 13, c = -13;

5) (5 + 2x)(4x - 1) - 2(2 + 3x) = -13x²,

    20x - 5 + 8x² - 2x - 4 - 6x + 13x² = 0,

    21x² + 12x - 9 = 0,

     7x² + 4x - 3 = 0,

     a = 7, b = 4, c = -3;

6) (2 - 6x)(x - 4) - 3x(1 - x) = -22x²,

    2x - 8 - 6x² + 24x - 3x + 3x² + 22x² = 0,

    19x² + 23x - 8 = 0,

    a = 19, b = 23, c = -8.