2. Efectuați calculele: (x-7)(2x-1)-(√2x)²; a) c) 7x(x - 5)-4x(x-8)(√3x)²; b) (√3x)² - 3(x + 1)(x + 2) + 9x; d) 5x(x-3) - 3x(x-4)-(√√2x)².​