1. y = eˣ - 5 x⁵ /4 + 7sinx - 1/x + 4x 2. y = (3x³ + 6x) (2x² - 4x) 3. y = x²/2-x²

1) (y)\' = e^x - 25 * x^4 / 4 + 7cos(x) + 1/x^2 + 4.

2) (y)\' = (9x^2 + 6) * (2x^2 - 4x) + (3x^3 + 6x) * (4x - 4).

3) (y)\' = ((x^2)\' * (2 - x^2) - x^2 * (2 - x^2)\') / (2 - x^2)^2 = (2x * (2 - x^2) - x^2 * (-2x)) / (2 - x^2)^2 = 2x * (2 - x^2 + x^2) / (2 - x^2)^2 = 4x / (2 - x^2)^2.