2017 年广西桂林电子科技大学数学专业英语考研真题 A 卷
英译汉
1.
(1) straight line
(2) even integer
(3) positive number
(4) x to the minus two thirds
(5) complex-valued sequence
(6) the second derivative
2. Before 17th century, man confined himself to the elementary mathematics, i.e.,
geometry, trigonometry and algebra, in which only the constants were considered.
3. A circle is a closed curve lying in one plane, all points of which are equidistant
from a fixed point called the center.
4. Two sets A and B are said to be equal if they consist of exacly the same elements,
in which case we write A=B. If one of the sets contains and element not in the
other, we say the sets are unequal and we write A B .
5. Theorem 1. A monotonic sequence converges if only if it is bounded.
Note: A sequence { ( )}
f n
is called bounded if there exists a positive number
M such that
|
( ) | M foralln.
f n
A sequence that is not bounded is called unbouned.
Proof: It is clear that an unbounded sequence cannot converge. Therefore,
all we need to prove is that a bounded monotonic sequence must converge.
Assume
values. Then
( )
f n and let L denote the least upper bound of the set of function
( ) L
f n
for all n, and we shall prove that the sequence converges
to L.
Choose any positive number . Since L
(
)
f N
( )
f n , we must have
all numbers
L
cannot be an upper bound for
for some N. … From these
inequalities we find that
0 L-f(n)<
for all n N
and this means that the sequence converges to L, as asserted.
( )
f n , the proof is similar, the limit in this case being the greatest low
If
bound of the set of function values.