Question
f(x) is a quadratic function whose graph has a vertex at the point (-3 , 2) and has a y-intercept at the point (0 , -16).
Find the equation for function f(x).
Find the x-intercepts of the graph of f(x).
f(x) is a quadratic function whose graph has a vertex at the point (-3 , 2) and has a y-intercept at the point (0 , -16).
Find the equation for function f(x).
Find the x-intercepts of the graph of f(x).
Since the vertex of the quadratic function is at the point (-3 , 2),
The equation for function is
f(x)=a(x+3)^2+2
Since the function has a y-intercept at the point (0 , -16), we get the following equation
-16 = a(0+3)^2+2
Solve the equation
a = -2
Therefore, the equation for quadratic function is
f(x)=-2(x+3)^2+2
If f(x) = 0,
-2(x+3)^2+2 = 0
(x+3)^2=1
x+3=\pm 1
x=-2 and x=-4
Therefore, the x-intercepts of the graph of f(x) are points (-4,0) and (-2,0)