Answer:
The equation of the horizontal line passing through (4, 9) will be:

Please also check the attached line graph.
Step-by-step explanation:
We know that the equation of a horizontal line is always the kind of equation such as:

- As in the pint (4, 9), ordinate is 9.
- In other words, y=9
Thus, the equation of the horizontal line passing through (4, 9) will be:

Please also check the attached line graph.
Step-by-step explanation:
Step 1: Simplify both sides of the equation.
x2−2x−8=0
Step 2: Factor left side of equation.
(x+2)(x−4)=0
Step 3: Set factors equal to 0.
x+2=0 or x−4=0
x=−2 or x=4