Question

What is the y-value of the vertex of the function f(x) = –(x – 3)(x + 11)?

Answer 1

Expand
f(x)=-1x^2-8x+33

x coordinate of vertex is -b/2a in the form ax^2+bx+c=y
a=-1
b=-8
-(-8)/2(-1)=8/-2=-4
plug back in to get y value

y=-(-4^2)-8(-4)+33
y=-16+32+33
y=49

y value is 49