a) 5(2x - 1)² + 4(x - 1)(x + 3) - 2(5 - 3x)²
= 5[(2x)² - 2.2x.1 + 1²) + 4(x² + 3x - x - 3) - 2(5² - 2.5.3x + (3x)²]
= 5(4x² - 4x + 1) + 4x² + 12x - 4x - 12 - 2(25 - 30x + 9x²)
= 20x² - 20x + 5 + 4x² + 12x - 4x - 12 - 50 + 60x - 18x²
= 6x² + 48x - 57
b) (9x - 1)² + (1 - 5x)² + 2(9x - 1)(1 - 5x)
= (9x - 1 - 1 - 5x)(9x - 1 + 1 + 5x) + 2(9x - 45x² - 1 + 5x)
= 56x - 24x + 18x - 50x² - 2 + 10x
= 60x - 2
c) (2a² + 2a + 1)(2a² - 2a + 1) - (2a² + 1)²
= (2a² + 1)² - 4a² - (2a² + 1)²
= -4a²