On stability of delay equations with positive and negative coefficients with applications

We obtain new explicit exponential stability conditions for linear scalar equations with positive and negative delayed terms $$\dot{x}(t)+\sum _{k=1}^m{a}_k(t)x(h_k(t))-\sum _{k=1}^l{b}_k(t)x(g_k(t))=0$$ and its modifications, and apply them to investigate local stability of Mackey–Glass type models $$\dot{x}(t)=r(t)[\beta \frac{x(g(t))}{1+x^n(g(t))}-\gamma x(h(t))]$$ and $$\dot{x}(t)=r(t)[\beta \frac{x(g(t))}{1+x^n(h(t))}-\gamma x(t)]\mathrm{.}$$