Answer:
lim
(
1−
5−x
3−
5+x
)
=
x→4
{
(1−
(3−
×
(3+
(1+
}
{1−(5+x)}(3+
{9(5+x)}(1+
−(4−x)(3+
(4−x)(1+
−(3+
9
1+
1
−6
2
=−
3
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