What is the the vertex of y =-2x^2 + 12x + 9 y=−2x2+12x+9?
1 Answer
Jun 4, 2018
Explanation:
"given a quadratic in "color(blue)"standard form ";ax^2+bx+cgiven a quadratic in standard form ;ax2+bx+c
"then the x-coordinate of the vertex is "then the x-coordinate of the vertex is
•color(white)(x)x_(color(red)"vertex")=-b/(2a)∙xxvertex=−b2a
-2x^2+12x+9" is in standard form"−2x2+12x+9 is in standard form
"with "a=-2,b=12" and "c=9with a=−2,b=12 and c=9
x_("vertex")=-12/(-4)=3xvertex=−12−4=3
"substitute this value into the equation for y"substitute this value into the equation for y
y_("vertex")=-2(3)^2+12(3)+9=27yvertex=−2(3)2+12(3)+9=27
color(magenta)"vertex "=(3,27)vertex =(3,27)
