Answer:
a)
![\\eg \forall x :x>5 \equiv \forall x:x\leq 5](https://img.qammunity.org/2020/formulas/mathematics/college/iuer32ohg1ma2il6bjmsh4jdau3qzuzj93.png)
b)
or the set
![\{x:x\\eq-1\}](https://img.qammunity.org/2020/formulas/mathematics/college/c9zpzc2zgrtfe5g9rkxi6e8g5y8hcrut1w.png)
Explanation:
First, notice that in both cases we have to sets:
a) is the set of all real numbers which are higher than 5 and in
b) the set is the solution of the equation
which is the set
![x=-1](https://img.qammunity.org/2020/formulas/mathematics/high-school/whlztoonow2sjij0bijxz0wnqgda4xeqq1.png)
De Morgan's Law for set states:
, being
and
are the complements of the sets
and
.
is the union operation and
the intersection.
Thus for:
a)
. Notice that
is the complement of the given set.
b)
which is the set