Jambmaths question:
Find the range of values of m which satisfy $(m-3)(m-4)<0$
Option A:
$2<m<5$
Option B:
$-3<m<4$
Option C:
$3<m<4$
Option D:
$-4<m<3$
Jamb Maths Solution:
Draw what I call a range table to determine this condition will be satisfied.
|
|
m < 3 |
3 < m < 4 |
m > 4 |
|
m – 3 |
– |
+ |
+ |
|
m – 4 |
– |
– |
+ |
|
(m – 3)( m – 4) |
+ |
– |
+ |
Since the range 3 < m < 4 gives a negative value., the inequality $(m-3)(m-4)<0$ is true within this range. The others gives a positive value, so we ignore them
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