

The original function is
Write
as
or
First solve the case
.
Apply subtraction property of equality: if a = b, then a - c = b - c.
\
(Subtract 9 from each side)
(Additive inerse property:
)
(Additive identity property:
)
(Subtract:
)
Next solve the case
.
(Subtract 9 from each side)
(Additive inerse property:
)
(Additive identity property:
)
(Subtract:
)
First, draw a number line.
\To graph the solutions set, mark the numbers –7 and –9 on number line.
\
The solution set is
.