SOLUTION: Graph the parabola: y=-x^2-10x-20 Plot the vertex and four additional points, two on each side of the vertex.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: Graph the parabola: y=-x^2-10x-20 Plot the vertex and four additional points, two on each side of the vertex.      Log On


   

Question 1006903: Graph the parabola:
y=-x^2-10x-20
Plot the vertex and four additional points, two on each side of the vertex.
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Identify at least the x-coordinate of the vertex.
referring to ax^2+bx+c,
a=-1,b=-10
Vertex goes through line of symmetry x=-b%2F%282a%29
x=-%28-10%29%2F%28-2%2A1%29
x=-5


The line of symmetry, which goes through the vertex, is found from the general form equation using completing the square to put into standard form, allowing the vertex coordinates to be read from the equation.

For other points to pick and plot, pick any two x values to the left of -5 and any two values to the right of -5, and find the y values for each of them.

graph%28300%2C300%2C-10%2C6%2C-6%2C10%2C-x%5E2-10x-20%29