Motivated forgetting is a theorized psychological behavior in which people may forget unwanted memories, either consciously or unconsciously. It is not a defence mechanism, since these are unconscious coping techniques used to reduce anxiety arising from unacceptable or potentially harmful impulses.
Each of these ODEs is linear and homogeneous with constant coefficients, so we only need to find the roots to their respective characteristic equations.
(a) The characteristic equation for
is
which arises from the ansatz 
.
The characteristic roots are 
and 
. Then the general solution is
where 
are arbitrary constants.
(b) The characteristic equation here is
with a root at 
of multiplicity 2. Then the general solution is
(c) The characteristic equation is
with roots at 
, where 
. Then the general solution is
Recall Euler's identity,
Then we can rewrite the solution as
or even more simply as
Answer: A. Paris is an old city, but some is even more ancient.
Explanation:
A is a compound sentence because the there are two complete sentences in the sentence. “Paris is an old city” is a complete sentence. “Some is even more ancient” is another full sentence. If there are two or more complete sentence separated by a conjunction, then It is a compound sentence. B is not a compound sentence, because there is only one complete sentence.
