Answer:
S(x) = x² + 390224/x
Step-by-step explanation:
Volume of the open box = V = 97556 cm³
Material needed:
Let´s call x the side of the square base then the area of the base is
A(b) = x²
For the sides of the box, we have 4 sides each one with area of x*h
where h is the height of the box
The volume of the box V(b) = 97556 = x²*h then h = 97556/x²
S(x,h) = x² + 4*x*h*
The surface area of the box as function of x is:
S(x) = x² + 4*x*97556/x²
S(x) = x² + 390224/x
y = x^2 + 2x...eqn 1
y = 3x + 20...eqn 2
subst for y in eqn 1...
=> x^2 +2x = 3x +20
=> x^2 - x - 20 =0
=> (x-5) (x+4) =0
=> x = 5 or -4
for x =5, y = 35 (sub for x in eqn 1 or 2)
for x = -4, y = 8 (sub for x in eqn 1 or 2)
I think the answer could be C
