The solution to the differential equation
$$\frac { \mathrm { d } y } { \mathrm {~d} x } = | - 6 x | \quad \text { for all } x$$
is $y = f ( x ) + c$, where $c$ is a constant.
Which one of the following is a correct expression for $f ( x )$ ?
..... 21
The solution to the differential equation

$$\frac { \mathrm { d } y } { \mathrm {~d} x } = | - 6 x | \quad \text { for all } x$$

is $y = f ( x ) + c$, where $c$ is a constant.

Which one of the following is a correct expression for $f ( x )$ ?