Korean J. Math. Vol. 19 No. 3 (2011) pp.309-319
DOI: https://doi.org/10.11568/kjm.2011.19.3.309

OSCILLATION CRITERIA OF DIFFERENTIAL EQUATIONS OF SECOND ORDER

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Rak Joong Kim

Abstract

We give sufficient conditions that the homogeneous dif-
ferential equations : for t ≥ t0 (> 0),
x′′ (t) + q(t)x′ (t) + p(t)x(t) = 0,
x′′ (t) + q(t)x′ (t) + F (t, x(φ(t))) = 0
are oscillatory where 0 ≤ φ(t), 0 < φ′ (t), $\lim_{t\rightarrow \infty} φ(t)$ = ∞ and F (t, u) ·
sgn u ≥ p(t)|u|. We obtain comparison theorems.



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