a/ \(y'=\frac{\left(2-5x-x^2\right)'}{2\sqrt{2-5x-x^2}}=\frac{-5-2x}{2\sqrt{2-5x-x^2}}\)
b/ \(y'=\frac{\left(x^3-2x^2+1\right)'}{2\sqrt{x^3-2x^2+1}}=\frac{3x^2-4x}{2\sqrt{x^3-2x^2+1}}\)
c/ \(y'=\frac{1}{\sqrt{x}}+\frac{\left(5-4x\right)'}{2\sqrt{5-4x}}=\frac{1}{\sqrt{x}}-\frac{2}{\sqrt{5-4x}}\)