Answer:
The dimensions of the box that minimize the materials used is 
Step-by-step explanation:
Given : An open top box is to be built with a rectangular base whose length is twice its width and with a volume of 36 ft³.
To find : The dimensions of the box that minimize the materials used ?
Solution :
An open top box is to be built with a rectangular base whose length is twice its width.
Here, width = w
Length = 2w
Height = h
The volume of the box V=36 ft³
i.e. 

The equation form when top is open,

Substitute the value of h,



Derivate w.r.t 'w',

For critical point put it to zero,





Derivate the function again w.r.t 'w',

For w=3, 
So, it is minimum at w=3.
Now, the dimensions of the box is
Width = 3 ft.
Length = 2(3)= 6 ft
Height = 
Therefore, the dimensions of the box that minimize the materials used is 
Use the given formula
C = 2(pi)r
Given pi = 3.14, r = 4
C = 2(3.14)(4) = 25.12 inches
Solution: 25.12 inches
Answer:
28 is your answer
Step-by-step explanation:
you start with multiplication and continue with addition and then go to subtraction

Notice that

So as

you have

. Clearly

must converge.
The second sequence requires a bit more work.

The monotone convergence theorem will help here; if we can show that the sequence is monotonic and bounded, then

will converge.
Monotonicity is often easier to establish IMO. You can do so by induction. When

, you have

Assume

, i.e. that

. Then for

, you have

which suggests that for all

, you have

, so the sequence is increasing monotonically.
Next, based on the fact that both

and

, a reasonable guess for an upper bound may be 2. Let's convince ourselves that this is the case first by example, then by proof.
We have


and so on. We're getting an inkling that the explicit closed form for the sequence may be

, but that's not what's asked for here. At any rate, it appears reasonable that the exponent will steadily approach 1. Let's prove this.
Clearly,

. Let's assume this is the case for

, i.e. that

. Now for

, we have

and so by induction, it follows that

for all

.
Therefore the second sequence must also converge (to 2).
Answer:
yes
Step-by-step explanation:
If 2 lines are perpendicular then the product of their slopes = - 1
The equation of a line in slope- intercept form is
y = mx + c ( m is the slope and c the y- intercept )
y = - x - 4 ← is in slope- intercept form
with slope m = - 1
5x - 5y = 20 ( subtract 5x from both sides )
- 5y = - 5x + 20 ( divide all terms by - 5 )
y = x - 4 ← in slope- intercept form
with slope m = 1
Thus product of their slopes is - 1 × 1 = - 1
Therefore the lines are perpendicular