f'(y) = 3 - 5 / (2 - 5x)^2
f'(y) = (2 1/2x^-1) + (-6 x^-2) + (1 + tg^2(x)) - 4cos(x)
f'(y) = (cos(x) * x - sin(x)) / x^2
f'(y) = x^2 * (1/cos^2(x)) + 2xtg(x)
f'(y) = (5x^4 + 4x^3 + 3) - (x^5 + x^4 + 3) / x^2
f'(y) = 3 - 5 / (2 - 5x)^2
f'(y) = (2 1/2x^-1) + (-6 x^-2) + (1 + tg^2(x)) - 4cos(x)
f'(y) = (cos(x) * x - sin(x)) / x^2
f'(y) = x^2 * (1/cos^2(x)) + 2xtg(x)
f'(y) = (5x^4 + 4x^3 + 3) - (x^5 + x^4 + 3) / x^2