A box with a square base and open top must have a volume of 157216 cm3. We wish to find the dimensions of the box that minimize the amount of material used. First, find a formula for the surface area of the box in terms of only x, the length of one side of the square base.
[Hint: use the volume formula to express the height of the box in terms of x.]
Simplify your formula as much as possible.
A(x)=
Next, find the derivative A′(x).
A'(x)=
Now, calculate when the derivative equals zero, that is, when A′(x)=0. [Hint: multiply both sides by x2.]
A'(x)=0 when x=
We next have to make sure that this value of x gives a minimum value for the surface area. Let's use the second derivative test. Find A"(x).
A"(x)=
Evaluate A"(x) at the x-value you gave above.

Step-by-step explanation:

Given a box with a square base and an open top which must have a volume of 157216 cubic centimetre. We want to minimize the amount of material used.

Step 1:

Let the side length of the base =x

Let the height of the box =h

Since the box has a square base

Volume

Surface Area of the box = Base Area + Area of 4 sides

Step 2: Find the derivative of A(x)

Step 3: Set A'(x)=0 and solve for x

Step 4: Verify that x=68 is a minimum value

We use the second derivative test

Since the second derivative is positive at x=68, then it is a minimum point.

Recall:

Therefore, the dimensions that minimizes the box surface area are:

the correct option is 2.

step-by-step explanation:

according to the given information triangle abc is a right angle triangle with right angle at a. segment ab is 5 and segment ac is 7. point d is on segment bc and angles adb and adc are right angles.

it is given that triangles abd, cad, and cba are similar.

two triangles are similar if their corresponding sides are proportional.

in triangle cba, using pythagoras theorem

                      )

triangle abd and cba are similar,

                            (2)

triangle cad and cba are similar,

                      )

using (1), (2) and (3), we get

hence proved.

therefore option 2 is correct.