she will need 18 boxes total :)
I am pretty sure the answer is c
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Answer:
y = -2/3x - 3
Step-by-step explanation:
y = mx + b
m = slope
(-3,-1) = (x,y)
<em>Plus in the coordinates</em>
-1 = -2/3(-3) + b
<em>negative times negative = positive</em>
-2/3 * -3 = 2
-1 = 2 +b
<em>Use inverse operations</em>
-2 --2
-3 = b
y = -2/3x - 3
We can create two equations here:
(1) Volume = area of square * height of box
85.75 = s^2 h
(2) Cost = 3 * area of square + 1.5 * area of side box
C = 3 s^2 + 1.5 s h
From (1), we get:
h = 85.75 / s^2
Combining this with (2):
C = 3 s^2 + 1.5 s (85.75 / s^2)
C = 3 s^2 + 128.625 s-
Taking the 1st derivative and equating dC/ds =
0:
dC/ds = 6s – 128.625 / s^2 = 0
Multiply all by s^2:
6s^3 – 128.625 = 0
6s^3 = 128.625
s = 2.78 cm
So h is:
h = 85.75 / s^2 = 85.75 / (2.78)^2
h = 11.10 cm
So the dimensions are 2.78 cm x 2.78 cm x 11.10 cm
The total cost now is:
C = 3 (2.78)^2 + 1.5 (2.78) (11.10)
C = $69.47