8. Given that $a$ and $b$ are the x-coordinates of the points where the parabola $y=(x-c)(x-c-d)-2$ intersects the x-axis, and $a<b$. Then the value of $|a-c|+|c-b|$ is $\qquad$
$8 . b-a$.
When $x=c$, $y=-2$, which means the point $(c,-2)$ is on the parabola and below the $x$-axis. Since the parabola $y=(x-c)(x-c-d)-2$ opens upwards, from the graph we can see that the value of $c$ lies between $a$ and $b$, i.e., $a<c<b$. Simplifying, we get $b-a$.