Question

Question #c5316

Answer 1

`(2,11),x=2`

Explanation:

`"given the equation of a parabola in standard form"`

`•color(white)(x)y=ax^2+bx+c color(white)(x);a!=0`

`"then the x-coordinate of the vertex which is also the"`
`"axis of symmetry is"`

`x_(color(red)"vertex")=-b/(2a)`

`f(x)=-x^2+4x+7" is in standard form"`

`"with "a=-1,b=4,c=7`

`rArrx_(color(red)"vertex")=-4/(-2)=2`

`"substitute this value into the equation for y-coordinate"`

`rArry_(color(red)"vertex")=-4+8+7=11`

`rArrcolor(magenta)"vertex "=(2,11)`

`"axis of symmetry is "x=2`