Answer:
![h = \sqrt[3]{\frac{49V}{4}}](https://tex.z-dn.net/?f=h%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B49V%7D%7B4%7D%7D)
Step-by-step explanation:
Represent the volume of the box with V and the dimensions with l, b and h.
The volume (V) is:

Make h the subject of the formula

The surface area (S) of the aquarium is:

Where lb represents the area of the base (i.e. slate):
The cost (C) of the surface area is:



Substitute
for h in the above equation



Differentiate with respect to l and with respect to b


To solve for b and l, we equate both equations and set l to b (to minimize the cost)


By comparison:

becomes

Cross Multiply

Solve for l

![l = \sqrt[3]{\frac{2V}{7}}](https://tex.z-dn.net/?f=l%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B2V%7D%7B7%7D%7D)
Recall that: 
![b = \sqrt[3]{\frac{2V}{7}}](https://tex.z-dn.net/?f=b%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B2V%7D%7B7%7D%7D)
Also recall that:

![h = \frac{V}{\sqrt[3]{\frac{2V}{7}}*\sqrt[3]{\frac{2V}{7}}}](https://tex.z-dn.net/?f=h%20%3D%20%5Cfrac%7BV%7D%7B%5Csqrt%5B3%5D%7B%5Cfrac%7B2V%7D%7B7%7D%7D%2A%5Csqrt%5B3%5D%7B%5Cfrac%7B2V%7D%7B7%7D%7D%7D)
![h = \frac{V}{\sqrt[3]{\frac{4V^2}{49}}}](https://tex.z-dn.net/?f=h%20%3D%20%5Cfrac%7BV%7D%7B%5Csqrt%5B3%5D%7B%5Cfrac%7B4V%5E2%7D%7B49%7D%7D%7D)
Apply law of indices
![h = \sqrt[3]{\frac{49V^3}{4V^2}}](https://tex.z-dn.net/?f=h%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B49V%5E3%7D%7B4V%5E2%7D%7D)
![h = \sqrt[3]{\frac{49V}{4}}](https://tex.z-dn.net/?f=h%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B49V%7D%7B4%7D%7D)
The dimension that minimizes the cost of material of the aquarium is:
![h = \sqrt[3]{\frac{49V}{4}}](https://tex.z-dn.net/?f=h%20%3D%20%5Csqrt%5B3%5D%7B%5Cfrac%7B49V%7D%7B4%7D%7D)
0.07 * 1.22
Is equal to 0.0854
Answer:
The side length of the original square was 6 inches
Step-by-step explanation:
we know that
The area of a square is

where
b is the length side of the square
Let
x ---> the length of the original square
The area of the original square is

The length of the smaller square is

The area of the smaller square is

The area of the smaller square is 1/4 the area of the original square
so

solve for x

Multiply by 4 both sides


Solve the quadratic equation by graphing
using a graphing tool
x=2, x=6
see the attached figure
The solution is x=6 in
Remember that the solution must be greater than 3 inches (because Stacey cuts 3 inches off of the length of the square and 3 inches off of the width)
therefore
The side length of the original square was 6 inches
Answer:
The equation that Deon can use to find the time 't' it takes for his ride is t=distance/rate or t=15/20 or 0.75 hours.
Step-by-step explanation:
The relationship between distance, rate and time is a common formula represented by d=rt where 'd'=distance, 'r'=rate and 't'=time. Distance is typically calculated in miles, where rate is given in miles/hour and time is the hours. In this case, because we are looking for 't', we would simply plug in the values of distance and rate to get 20=15t. In order to solve for 't', we need to use inverse (opposite) operations, dividing both sides by 15 and getting 0.75 hours for 't'.
Answer:
It will take Lin an hour and 25 minutes at her constant speed, and it will take Jada at her constant speed an hour and 30 minutes.
SO, Lin will arrive at 4:25
and Jada will arrive at 4:30
There is a 5 minute difference in time.
Step-by-step explanation:
From the facts given, Lin can walk 13 miles in 5 hours which when you divide means she can walk 2.6 mph (miles per hour), and Jada can walk 2.5 mph.
To get these answers you divide the current speeds into the total distance
For example, in Lin's case...
3.25 (The 3 and 1/4 mile converted to decimal form)
2.6 (Lin's Average speed per hour)
3.25/2.6=1.25
1.25 (1 hour and 25 minutes)