Let us consider the system in the form

where
,
and
,
If we represent the matrix A in the form

then

Let us find step by step the blocks
and Ui:
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To solve system (13), one must first solve the system

We find that
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Secondly, we have to solve the system

Example 6.6.1.* Let us solve the system
of equations
where

This is a block system given by relation (13) since

where
and
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We will express the matrix A in the form


Now we find
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and

To find a solution of the system
,
we shall solve two systems
and
The system
can be expressed in the form

where
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and
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Solving the system
which can be given in the form

we obtain
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Thus,
