D. The exclusion is important because we cannot divide by zero. Apart from that we are simply looking at a function.
When the slope isn't defined, it's not possible to write the line in slope-intercept form. No slope means a vertical line, which here must be

The ordered pair (-1,6) obviously satisfies the above equation so is on the vertical line
.
Answer:
arc ADB = 270°
Step-by-step explanation:
Arc ADB is the remainder of the circle after subtracting 90° arc AB. Its measure is ...
ADB = 360° -90° = 270°
Answer:
OPTION A: Divide both the sides by 5
Step-by-step explanation:
We are given: 5z - 3 = 12
When we add 9 to both sides we get:
5z - 3 + 9 = 12 + 9
⇒ 5z + 6 = 21
⇒ 5z = 21 - 6 = 15
⇒ 5z = 15
To find the value of z we have to divide both the sides by 5.
i.e., 
⇒ z = 3.