SOLUTION: Find the vertex of the function f(x) = -2x^2 - 12x +- 28. You’ll need to put it in the form of f(x)= a(x – h)^2 + k. Explain how you use this to find the vertex and how to graph th

Algebra ->  Functions -> SOLUTION: Find the vertex of the function f(x) = -2x^2 - 12x +- 28. You’ll need to put it in the form of f(x)= a(x – h)^2 + k. Explain how you use this to find the vertex and how to graph th      Log On


   

Question 932692: Find the vertex of the function f(x) = -2x^2 - 12x +- 28. You’ll need to put it in the form of f(x)= a(x – h)^2 + k. Explain how you use this to find the vertex and how to graph the equation of the quadratic. What does “a” tell you? Describe the graph. thanks.
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
Find the vertex of the function f%28x%29+=+-2x%5E2-12x-28.
You’ll need to put it in the form of
f%28x%29=+a%28x+-h%29%5E2+%2B+k.
a,h, and k are just constant that affect exactly where the quadratic is placed on the graph and what it looks like
a shows us is parabola opens up or down
h, and k are the coordinates of the vertex


f%28x%29+=+-2x%5E2-12x+-28.. ...complete the square
f%28x%29+=+%28-2x%5E2+-12x%2B___%29-28
f%28x%29+=-2%28x%5E2+%2B6x%2B___%29-28
f%28x%29+=-2%28x%5E2+%2B6x%2B3%5E2%29-%28-2%29%2A3%5E2-28
f%28x%29+=-2%28x%2B3%29%5E2+%2B18-28
f%28x%29+=-2%28x%2B3%29%5E2-10

a=-2=> a%3C0... so, =>x%5E2 coefficient is negative hence parabola open down
the coordinates of the vertex are:
h=-3
k=-10
so, the vertex is at (-3,-10)

+graph%28+600%2C+600%2C+-10%2C+10%2C+-20%2C+10%2C+-2%28x%2B3%29%5E2-10%29+