Answer:
x = 10 cm, y = 5 cm gives a minimum area of 300 cm^2.
Step-by-step explanation:
V= x^2y = 500
Surface area A = x^2 + 4xy.
From the first equation y = 500/x^2
So substituting for y in the equation for the surface area:
A = x^2 + 4x * 500/x^2
A = x^2 + 2000/x
Finding the derivative:
dA/dx = 2x - 2000x^-2
dA/dx = 2x - 2000/x^2
This = 0 for a minimum/maximum value of A, so
2x - 2000/x^2 = 0
2x^3 - 2000 = 0
x^3 = 2000/ 2 = 1000
x = 10
Second derivative is 2 + 4000/x^3
when x = 10 this is positive so x = 10 gives a minimum value of A.
So y = 500/x^2
= 500/100
= 5.
A.
B.
It's a minimum, becuase 
.
C.
The axis of symmetry is 
. So, in this case, it's 
.
Answer: Its c 8-10
Step-by-step explanation:
Answer: C. y = 10x + 15
Step-by-step explanation:
He has already watched 15 movies so that's plus 15
And now he wants to watch 10 movies per week, we don't know how many weeks so that's '<em>x</em>' in this equation.
If he watches movies for <em>x </em>weeks that's 10 times <em>x </em>which is the 10x in the equation.
Hope that helped!
