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Question 621129: Give the coordinates of the vertex and graph the coordinates of the parabola?
y=x^2+2x+4
I know the vertex is (-1,3) and I can easily plot that on the graph but what is the other point I have to plot in order to graph the parabola? I'm having a hard time with the graphing part.
Answer by solver91311(24713)   (Show Source):
You can put this solution on YOUR website!
Calculate the value of ) which will be the  -coordinate of the -intercept. With a quadratic in standard form, this is simply the constant term. So your -intercept is ) . Plot that point.
Next, remember the property of symmetry. If there is a function value of  at  units from the vertex, then there is a point on the parabola units on the OTHER SIDE of the vertex with the same function value.
So, if your vertex is at an  -value of -1, and the function has a value of 4 at a point 1 unit to the right of the vertex (-1 + 1 = 0), then the graph will have a point 1 unit to the left of the vertex at the same function value. That is, plot the point )
Next, you can just pick any value (other than the ones already used) for and calculate the function value. That will give you two different points on the graph because of the symmetry property we just talked about.
Have fun.
John
My calculator said it, I believe it, that settles it
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