Calculus 1 : Calculus

Study concepts, example questions & explanations for Calculus 1

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Example Questions

Example Question #81 : How To Find Rate Of Change

A right triangle has two legs of lengths  and . The longer leg is growing at a rate of . What is the rate of change of the shorter leg if the hypotenuse is not currently changing length?

Possible Answers:

Correct answer:

Explanation:

The hypotenuse's length relation to the legs of a right triangle is shown by the Pythagorean Theorem:

This theorem can also be used to show how the rates of change of each parameter relate if we take the derivative of each side of the equation with respect tot ime:

 or simply 

Treating  as the smaller side and  as the longer side, . Since the hypotenuse is not changing length at the moment, .  This allows us to plug in terms into the above equation:

(In this case, it was unnecessary to calculate that )

Solving for :

Example Question #81 : How To Find Rate Of Change

 where , and  all change with respect time.  When  and  changes at rate of  and  changes at rate of . At what rate is  changing?

Possible Answers:

Correct answer:

Explanation:

 

The rate at which  changes is .  The find , we will find the first derivative of the equation

Since    and  both change with respect to time, so we must use the product rule when differentiating.

The product rule is .

The first derivative of  is 

We are given the following parameters

, and .

Subsituting these values into our derivative equation

 

 

Example Question #1973 : Functions

Find the rate of change of a line connected by the points  and .

Possible Answers:

Correct answer:

Explanation:

To find the rate of change of a line connected by two points.  We will use the following equation for slope.

The rate of change of the line is .

Example Question #1972 : Functions

A circle of radius  is inscribed inside of a square with sides of length . If the radius of the circle is expanding at a rate of , what is the rate of change of the sides such that the amount of area inscribed between the square and circle does not change? 

Possible Answers:

Correct answer:

Explanation:

The amount of area between the square and circle is given by the difference of the two individual areas, the larger and smaller:

It then holds that the rate of change of this difference in area can be found by taking the time derivative of each side of the equation:

We are told that the difference in area is not changing, which means that . Therefore:

Example Question #91 : How To Find Rate Of Change

A rectangle of length  and width  is changing shape. The length is shrinking at a rate of  and the width is growing at a rate of. At the moment the rectangle becomes a square, what will be the rate of change of its area?

Possible Answers:

Correct answer:

Explanation:

The area of a rectangle is given in terms of its length and width by the formula:

We are asked to find the rate of change of the rectangle when it is a square, i.e at the time that , so we must find the unknown value of  and  at this moment. The width and length at any time can be found in terms of their starting values and rates of change:

When they're equal:

And at this time .

Now, going back to our original area equation

We can take the derivative of each side with respect to time to find the rate of change:

Example Question #1973 : Functions

Find  if .

Possible Answers:

The derivative does not exist at that point.

Correct answer:

Explanation:

To find , we must first find the derivative and then plug in  for .

To evaluate this derivative, we need the following formulae:

Then plug in  for  into :

Example Question #91 : Rate Of Change

The length of a rectangle is defined by the function  and the width is defined by the function 

What is the rate of change of the rectangle's area at time  ?

Possible Answers:

Correct answer:

Explanation:

The area of a rectangle is given by the function:

For the definitions of the sides

 

The rate of change of the area can be found by taking the derivative of each side of the equation with respect to time:

Example Question #95 : How To Find Rate Of Change

The area of a circle is given by the function . What is the rate of change of the radius at time  ?

Possible Answers:

Correct answer:

Explanation:

The area of a circle is given by the function:

This equation can be rewritten to define the radius:

For the area function

The radius is then

or

The rate of change of the radius can be found by taking the derivative of each side of this equation with respect to time:

Example Question #96 : How To Find Rate Of Change

The rate of change of the area of a square is given by the function .

What is the rate of change of its sides at time ?

Possible Answers:

Correct answer:

Explanation:

The sides of a square and its area are related via the function

Rewriting the equation in terms of its sides gives

For the area definition

The sides are then

or

The rate of change can be found by taking the derivative of the equation with respect to time:

Example Question #97 : How To Find Rate Of Change

The sides of a cube are defined by the function .

What is the rate of growth of the cube's volume at time ?

Possible Answers:

Correct answer:

Explanation:

A cube's volume is defined in terms of its sides as follows:

For sides defined as

The volume is

The rate of change can be found by taking the derivative of the function with respect to time

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