I started having trouble on part (c), and I need to know this before

I can go onto the other problems. Plz help!

The parabola shown at the right (no picture, sorry) is of the form y=x^2+bx+c. The graph's y-intercept is (0,2), the axis of symmetry is -2.5 and the two points they show here is (-4,-2) and (-1,-2).
a. Use the graph to find the y-intercept. ( The y-intercept is (0,2) )
b. Find the equation of the axis of symmetry. ( x=-5/2 )
c. Use the vertex formula x=-b/2a to find b.
d. Write the equation of the parabola.
e. Test one point using the equation from part (d).
f. Would this method work if the value of a were not known? Explain.

Thanks for taking time to help me out people! Any help is greatly appreciated!

The value of a is 1 because x^2 has a coefficient of 1.

For part c, substitute -5/2 for x (axis of symmetry) to solve for b.

Therefore: -5/2 = -b/2(1); b = 5

For part d, you can determine the equation of the parabola by using one of the points, since you already know b.

y = x^2 + 5x + ?

Using one of the points (-4,-2):
-2 = (-4)^2 + 5(-4) + ?
-2 = 16 - 20 + ?
-2 = -4 + ?
2 = ?

Therefore: y = x^2 + 5x + 2

You can use the point (-1,-2) and achieve the same results.

This would answer part e as well.

This is just one method; there may be other ways to approach the same problem.

I hope this will help.

You guys are a GREAT help! Thanks so much for helping me out! You make everything sound so simple.

I'm glad I could help! Understanding the steps and methods to solve a problem can make it seem simpler. If you have any more questions or need further explanations, feel free to ask. Good luck with your other problems!