Answer:
Wyatt wrote the correct expression
Step-by-step explanation:
Here we are to evaluate which of the students wrote an expression with the highest common factor being 8c
For Tanya; 32c + 16c; 16c( 2 + 1); This is wrong as the highest common factor is 16c
For Wyatt, we have 8c - 48cd; factorizing, we have 8c(1-6cd); This is correct
For Xavier we have 36c-24c; 8 is not a factor of 36, so it won’t work
For Yang 8c + 40; 8(c+ 5); what we are trying to look for is 8c and not 8 so this is wrong also
Answer:
the rate of change of the water depth when the water depth is 10 ft is; 
Step-by-step explanation:
Given that:
the inverted conical water tank with a height of 20 ft and a radius of 8 ft is drained through a hole in the vertex (bottom) at a rate of 4 ft^3/sec.
We are meant to find the rate of change of the water depth when the water depth is 10 ft.
The diagrammatic expression below clearly interprets the question.
From the image below, assuming h = the depth of the tank at a time t and r = radius of the cone shaped at a time t
Then the similar triangles ΔOCD and ΔOAB is as follows:
( similar triangle property)


h = 2.5r

The volume of the water in the tank is represented by the equation:



The rate of change of the water depth is :

Since the water is drained through a hole in the vertex (bottom) at a rate of 4 ft^3/sec
Then,

Therefore,

the rate of change of the water at depth h = 10 ft is:




Thus, the rate of change of the water depth when the water depth is 10 ft is; 
Assuming ya mean

take derivitive
remember dy/dx e^x=e^x
also the chain rule
so

find where it equals 0


multiply both sides by e^x

divide both sides by 8

take ln of both sides


divide both sides by 9

x≈-1/5
f'(-1)<0
f'(0)>0
so it is increasing from x to infinity
the interval it is increasing on is