# Article

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Keywords:
Picone’s identity; forced quasilinear equation; principal solution
Summary:
We extend the classical Leighton comparison theorem to a class of quasilinear forced second order differential equations $(r(t)|x^{\prime }|^{\alpha -2}x^{\prime })^{\prime }+c(t)|x|^{\beta -2}x=f(t)\,,\quad 1<\alpha \le \beta ,\ t\in I=(a,b)\,, \qquad \mathrm {(*)}$ where the endpoints $a$, $b$ of the interval $I$ are allowed to be singular. Some applications of this statement in the oscillation theory of (*) are suggested.
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