(x + 9)(x + 12) = 0
Expanding the brackets, we get:
1.
the x value of the vertex in form
ax^2+bx+c=y
is
-b/2a
so
-2x^2+8x-18
x value of vertex is
-8/(2*-2)=-8/-4=2
plug it in to get y value
-2(2)^2+8(2)-18
-2(4)+16-18
-8-2
-10
vertex is at (2,-10)
or you could complete the square to get into y=a(x-h)^2+k, where the vertex is (h,k)
so as follows
y=(-2x^2+8x)-18
y=-2(x^2-4x)-18
y=-2(x^2-4x+4-4)-18
y=-2((x-2)^2-4)-18
y=-2(x-2)^2+8-18
y=-2(x-2)^2-10
vertex is (2,-10)
5.
vertex is the time where the speed is the highest
at about t=10, the speed is at its max
2 2/3 pages=8/3 pages
1 hour=60 minutes
Let x represent the total pages in an hour
8/3 pages in 5 minutes
x pages in 60 minutes
Use cross multiply
x(5)=8/3(60)
5x=160
Divided 5 to each side
5x/5=160/5
x=32 pages per hour. As a result, there will be 32 pages per hour. Hope it help!
