Solution As shown in the Fig 8 21, the line
y = 3x + 2 meets x-axis at x = 
32
−
 and its graph
lies below x-axis for
1, 32
x
−


∈ −



 and above
x-axis for 
32 ,1
x
−

∈


 Fig 8 21
X′
O
Y′
X
Y
S
L
L'
(��,�0)
a
Fig 8