Answer:
The minimum cost is $17.30c
Step-by-step explanation:
Given
--- Volume
--- cost of wall paint
---cost of ceiling paint
Required
Minimum cost of paint
The volume is calculated as:

Substitute 288 for V

Make z the subject

The surface area is calculated as:

Because xy represent the dimension of the ceiling and the opposite of the ceiling (the floor) will not be painted. Hence, it does not require a coefficient of 2
The cost is:

Substitute 





Differentiate w.r.t x and y


By comparison: 
Set them equal to 0


Substitute x for y


Cross multiply



Take the cube root of both sides
![x = \sqrt[3]{216}](https://tex.z-dn.net/?f=x%20%3D%20%5Csqrt%5B3%5D%7B216%7D)


Substitute 6 for x and for y in 




--- approximated
The answer would be C. 8 cm, 15 cm, 22cm.
The rule is that the two smaller sides when added, have to be bigger than the largest side. 8 + 15= 23 and the largest side is 22. 23 is greater than 22. The other options do not work with this rule
Answer:
96
Step-by-step explanation:
First collect like terms for x^2:
x^2 + 3x^2 = 5x^2
Then collect like terms for x:
-2x + 5x = 3x
Collect like terms for normal numbers:
7 + - 3 = 4
Put them altogether:
5x^2 + 3x + 4
$125 billion in scientific notation is 1.25*1011