# What is the the vertex of #y = -x^2 + 2x +4#?

##### 1 Answer

Jul 8, 2017

#### Explanation:

#"for a parabola in standard form " y=ax^2+bx+c#

#"the x-coordinate of the vertex is " x_(color(red)"vertex")=-b/(2a)#

#y=-x^2+2x+4" is in standard form "#

#"with " a=-1,b=2,c=4#

#rArrx_(color(red)"vertex")=-2/(-2)=1#

#"substitute into the equation for y-coordinate"#

#rArry_(color(red)"vertex")=-1+2+4=5#

#rArrcolor(magenta)"vertex "=(1,5)#

graph{-x^2+2x+4 [-10, 10, -5, 5]}