Answer:
, 
Step-by-step explanation:
The equations of volume and surface area are presented below:


The length of the tank is:

The expression fo the surface area is therefore simplified into an univariable form:


The first and second derivatives of the expression are, respectively:


The first derivative is equalized to zero and length of the square side is now found:



![l = \sqrt[3]{\frac{138}{4} }](https://tex.z-dn.net/?f=l%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B138%7D%7B4%7D%20%7D)

Now, the second derivative offers a criteria to determine if solution leads to an absolute minimum:

(Absolute minimum)
The depth of the tank is:


Answer:
12
Step-by-step explanation:
Stop asking for answers I’m a teacher stop!!!!! Now
Answer:
liked = 45 ; disliked = 18
Step-by-step explanation:
Let the number of songs he liked be x & disliked be y.
The ratio of x & y :-

And total number of songs he listened = 63
Then, x + y = 63...................eqn.1
=> x = 63 - y
Substituting the value of x in eqn. 2x = 5y gives :-
2(63 - y) = 5y
=> 126 - 2y = 5y
=> 7y = 126
=> y = 18
Substituting the value of y in eqn.1 gives
x = 63 - 18
= 45
Hence no. of songs he liked = 45 & disliked = 18