SOLUTION: Could you please explain to me how to find the vertex of the parabola given by: y= -2x^2 -3x + 8 ?

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: Could you please explain to me how to find the vertex of the parabola given by: y= -2x^2 -3x + 8 ?      Log On


   

Question 131739: Could you please explain to me how to find the vertex of the parabola given by: y= -2x^2 -3x + 8 ?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The vertex is at x+=+%28-b%29%2F%282a%29
where the equation is in the form
y+=+ax%5E2+%2B+bx+%2B+c
Your equation is:
y+=+-2x%5E2+-+3x+%2B+8
a+=+-2
b+=+-3
c+=+8
%28-b%29%2F%282a%29+=+%28-%28-3%29%29%2F%282%2A%28-2%29%29
%28-b%29%2F%282a%29+=+-%283%2F4%29
x+=+-%283%2F4%29
Now I have to find y
y+=+-2%2A%28-%283%2F4%29%29%5E2+-+3%2A%28-%283%2F4%29%29+%2B+8
y+=+-%2818%2F16%29+%2B+9%2F4+%2B+8
y+=+-%289%2F8%29+%2B+18%2F8+%2B+64%2F8
y+=+73%2F8
The vertex is at (-3/4 , 73/8)
I'll plot this to check
+graph%28+600%2C+600%2C+-4%2C+4%2C+-4%2C+12%2C+-2x%5E2+-+3x+%2B+8%29+