This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
There are 3 methods to find the vertex of quadratic functions f ( x ) = a x 2 + b x + c
For this question, I will demonstrate Method 2
f ( x ) = − 2 x 2 − 1 2 x − 2 1 = − 2 ( x 2 + 6 x + ( 2 6 ) 2 − ( 2 6 ) 2 ) − 2 1 = − 2 ( ( x + 3 ) 2 − 9 ) − 2 1 = − 2 ( x + 3 ) 2 + 1 8 − 2 1 = − 2 ( x + 3 ) 2 − 3
The vertex is ( − 3 , − 3 )
x = − 3 , y = − 3 , x + y = ( − 3 ) + ( − 3 ) = − 6