Hello,
x(x + 6) - x = x * x + x * 6 - x = x² + 6x - x = x² + 5x
x(y - 2) + xy = x * y + x * -2 + xy = xy - 2x + xy = 2xy - 2x
3x(x + 4) - 6x² = 3x * x + 3x * 4 - 6x² = 3x² + 12x - 6x² = -3x² + 12x
9x(x² - 6) + 2x² = 9x * x² + 9x - 6 + 2x² = 9x^3 - 54x + 2x²
5x(3 + 5x) + x(5 + x) + 4x(2x + 1) = 15x + 25x² + 5x + x² + 8x² + 4x = 34x² + 20x
