O Level Maths Notes: Solving Inequalities
Simple inequalities are are
very easy to solve. The process in very similar to making
the
subject of an equation, bearing in mind to have the inequality
instead of the equals sign throughout:
![]()
If the
sign
is replaced by any of
the
process is identical.
If we ever have to divide or
multiply by a minus number the
sign
has to point the other way. For example
![]()
The above equations are “one sided” inequalities but there are also “two sided” inequalities such as
![]()
To solve these inequalities
we have to make
the
sole term of the central term![]()
We add one to obtain
![]()
Then divide by 2 to obtain![]()
It may be required, if
is
a whole number or integer, to write down all the values of
which
satisfy the inequality.
For the inequality
may
only be equal to 2 or 4 since
so
is
greater than 2 and
so
is
less than 5.
To solve
follow
the same procedure as above, obtaining
and
note that now
may
be equal to 2, so
may
be![]()
To solve
follow
the same procedure as above, obtaining 2<=x<=5 and note that
now
may
be equal to 2 or 5, so
may
be![]()
To solve
follow
the same procedure as above, obtaining
and
note that now
may
not be equal to 2 but may be equal to 5, so
may
be![]()