2019
Том 71
№ 11

# Kuzina Yu. V.

Articles: 2
Brief Communications (Russian)

### Qualitative Investigation of the Singular Cauchy Problem F(t, x, x′) = 0, x(0) = 0

Ukr. Mat. Zh. - 2003. - 55, № 12. - pp. 1720-1723

We prove the existence and uniqueness of a continuously differentiable solution with required asymptotic properties.

Brief Communications (Ukrainian)

### Asymptotic Behavior of Solutions of the Cauchy Problem x′ = f(t, x, x′), x(0) = 0

Ukr. Mat. Zh. - 2002. - 54, № 12. - pp. 1698-1703

We prove the existence of continuously differentiable solutions $x:(0,{\rho ]} \to \mathbb{R}^n$ such that $$\left\| {x\left( t \right) - {\xi }\left( t \right)} \right\| = O\left( {{\eta }\left( t \right)} \right),{ }\left\| {x'\left( t \right) - {\xi '}\left( t \right)} \right\| = O\left( {{\eta }\left( t \right)/t} \right),{ }t \to + 0$$ or $$\left\| {x\left( t \right) - S_N \left( t \right)} \right\| = O\left( {t^{N + 1} } \right),{ }\left\| {x'\left( t \right) - S'_N \left( t \right)} \right\| = O\left( {t^N } \right),{ }t \to + 0,$$ where $${\xi }:\left( {0,{\tau }} \right) \to \mathbb{R}^n ,{ \eta }:\left( {0,{\tau }} \right) \to \left( {0, + \infty } \right),{ }\left\| {{\xi }\left( t \right)} \right\| = o\left( 1 \right),$$ $${\eta }\left( t \right) = o\left( t \right),{ \eta }\left( t \right) = o\left( {\left\| {{\xi }\left( t \right)} \right\|} \right),{ }t \to + 0,{ }S_N \left( t \right) = \sum\limits_{k = 2}^N {c_k t^k ,}$$ $$c_k \in \mathbb{R}^n ,k \in \left\{ {2,...,N} \right\},{ }0 < {\rho } < {\tau },{ \rho is sufficiently small}{.}$$