SOLUTION: what is the y-intercept for x^2-2x-8

Question 70015: what is the y-intercept for x^2-2x-8
Found 2 solutions by tutorcecilia, bucky:
Answer by tutorcecilia(2152) (Show Source): You can put this solution on YOUR website!
what is the y-intercept for x^2-2x-8
The y-intercept is the point where the parabola crosses the y-axis.
This value will always be (0, b) where x=0 (if there is a y-intercept).
.
So, let x=0 and solve for y:
y=x^2-2x-8
y=(0)^2-(0)-8
y=-8 or point (0, -8)

Answer by bucky(2189) (Show Source): You can put this solution on YOUR website!
Set y equal to the function you were given. This results in the equation:

Now think about the general structure of a graph. If you have a point on the Y-axis,
what is the value of X for that point. Every point on the Y-axis has a corresponding
X value of zero!!! Think of +3 on the Y-axis. This would be the point (0,+3). Similarly
the point -5 on the Y-axis would be (0, -5) and so on.
So for the above equation we can simply set x equal to zero to find the corresponding
value of y that satisfies the equation. Start with:

Plug in zero for x. This causes the terms that contain an x to be zero. What you are
left with is:
which simplifies to just
The Y-intercept occurs at y = -8 or at the point (0,-8). It's harder to explain than it
is to just set x equal to zero and determine what is left on the right side of the equation.
Hope this helps you understand how to find Y intercepts.
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