Answer: The correct answer is (B)
Step-by-step explanation: No. Ari should have written the percent ratio as 5/100
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
Given 4 boxes of pencils cost $5,
Unknown- slope
$1.25 per box since $5/boxes
Equation y=mx+b
Substitute $1.25/per box for m
Solve y=$1.25x
The Check
$5=$1.25/per box(4 boxes)
$5=$5
Answer:
Sorry don't know the answer
