What are the coordinates of the vertex of the graph of the function y = –3x² –12x + 3?
(1 point)
Responses
(–2, 29)
(–2, 29)
(2, –15)
(2, –15)
(2, –9)
(2, –9)
(–2, 15)
(–2, 15)
The correct answer is (−2,15)
y = –3x² –12x + 3
where is y = 0
x^2 + 4 x - 1 = 0
x = [ -4 +/- sqrt (16 +4) ] /2 = -2+/-.5sqrt 20
so vertex on x = -2
then what is y?
y = -3 [ x^2 + 4 x -1] = -3 [ 4 -8 -1] = -3 * -5 = 15
so sure enough
(-2 , 15 )