In this paper, we study oscillation of second-order functional differential equations with mixed nonlinearities ( p ( t ) x ′ ( t ) ) ′ + q ( t ) x ( t - τ ) + ∑ i = 1 n q i ( t ) | x ( t - τ ) | α i sgn x ( t - τ ) = e ( t ) , where τ ⩾ 0 , p ( t ) ∈ C 1 [ 0 , ∞ ) , q ( t ) , q i ( t ) , e ( t ) ∈ C [ 0 , ∞ ) , p ( t ) > 0 , α 1 > ⋯ > α m > 1 > α m + 1 > ⋯ > α n > 0 ( n > m ⩾ 1 ) . Without assuming that q ( t ) , q i ( t ) and e ( t ) are nonnegative, the results given in [Y.G. Sun, F.W. Meng, Interval criteria for oscillation of second-order differential equations with mixed nonlinearities, Appl. Math. Comput. 198 (2008) 375–381] have been extended to the aforementioned functional differential equation.
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