Precalculus : Pre-Calculus

Study concepts, example questions & explanations for Precalculus

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Example Questions

Example Question #4 : Solve Nonlinear Systems Of Equations

Solve the following system:

Possible Answers:

Correct answer:

Explanation:

Our first step is to solve the bottom equation for 

so we can substitute it into the top equation:

 

Now we can plug in our y-values into the bottom equation to find our x-values:

 

Remember we cannot take a square root of a negative number without getting an imaginary number. As such, we'll just focus on the  values.

 

Our solution is then: 

Example Question #5 : Solve Nonlinear Systems Of Equations

Solve the following system for :

Possible Answers:

Correct answer:

Explanation:

The first step is to solve the bottom equation for 

  since our question specifies for  we just focus on 

 

We now substitute this equation into the top equation:

 

we can now plug in our x-values into the bottom equation to find our y-values:

                        

                                     

                                               

                                                    

 

The solutions are then: 

Example Question #6 : Solve Nonlinear Systems Of Equations

Solve the following system:

Possible Answers:

Correct answer:

Explanation:

We can solve this equation by using substitution since the bottom equation is already solved for . Substituting the bottom equation into the top we get:

 We then solve the equation for our  values:

Finally, we substitute our values into the bottom equation to get our  values:

                         

                                      

                                 

Our different solutions are then: 

Example Question #821 : Pre Calculus

Solve the following system:

Possible Answers:

Correct answer:

Explanation:

We can substitute the top equation into the bottom:

 

and solve for  values:

Now that we have our  values we can plug it into the top equation and find our  values

                            

                       

 

So, our values are 

 

Example Question #1 : Solving Polynomial And Rational Inequalities

 

 

What is the solution to the following inequality?

Possible Answers:

Correct answer:

Explanation:

First, we must solve for the roots of the cubic polynomial equation.

We obtain that the roots are .

Now there are four regions created by these numbers:

 

  • . In this region, the values of the polynomial are negative (i.e.plug in  and you obtain 

 

  • . In this region, the values of the polynomial are positive (when , polynomial evaluates to )

 

  •  . In this region the polynomial switches again to negative.

 

  • . In this region the values of the polynomial are positive

 

Hence the two regions we want are  and .

 

Example Question #1 : Solve And Graph Rational Inequalities

Solve the inequality. 

Possible Answers:

Correct answer:

Explanation:

First, subtract  from both sides so you get 

.

Then find the common denominator and simplify 

.

Next, factor out the numerator 

 

and set each of the three factor equal to zero and solve for .

The solutions are 

.

Now plug in values between , and  into the inequality and observe if the conditions of the inequality are met.

Note that . They are met in the interval  and .

Thus, the solution to the inequality is  

Example Question #1 : Solving Polynomial And Rational Inequalities

Solve and graph:

Possible Answers:

Correct answer:

Explanation:

1) Multiply both sides of the equation by the common denominator of the fractions:

 

     

     

2) Simplify:

     

     

     

     

     

3) For standard notation, and the fact that inequalities can be read backwards:

    

 

     For interval notation:

      

4) Graph:

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Example Question #822 : Pre Calculus

Solve and graph:

Possible Answers:

Correct answer:

Explanation:

Graph the rational expression,

1) Because  and a divide by is undefined in the real number system, there is a vertical asymptote where .

2) As   ,   , and as  ,  .

3) As  ,  , and as   ,  .

4) The funtion y is exists over the allowed x-intervals:

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One approach for solving the inequality: 

For 

1) Determine where  over the x-values  or .

2)  for the intervals  or .

3) Then the solution is .

 

Another approach for solving the inequality:

1) Write   as , then determine the x-values that cause  to be true: 

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2)  is true for  or .

3) Then the solution is .

Example Question #2 : Solving Polynomial And Rational Inequalities

Which of the following best describes the statement:

The undefined points of rational functions are vertical asymptotes.

Possible Answers:

The statement is always false

The statement is true in some cases and false in others

The statement is always true

Correct answer:

The statement is always true

Explanation:

When solving for a point where the function will be undefined, you set the denominator equal to zero and solve for .  This creates a vertical asymptote because when the denominator equals zero the function is undefined and we are solving for .  Say for example a function is undefined at .  So at all values of where this function is undefined creating a vertical asymptote.

Example Question #5 : Solve And Graph Rational Inequalities

Which of the following is a graph of the function:

Possible Answers:

Screen shot 2020 08 21 at 2.55.37 pm

Screen shot 2020 08 21 at 2.56.12 pm

Screen shot 2020 08 21 at 2.56.17 pm

Correct answer:

Screen shot 2020 08 21 at 2.55.37 pm

Explanation:

We begin by finding the zeros of the equation using the numerator.

So we know that the function will equal zero when .  If we just look at the numerator of the function, then this graph would be a parabola with its point at .  Now we will solve for the points where the function is undefined by setting the denominator equal to zero and solving for .

 

 And so the function is undefined at .  If we make a table to solve for some of the points of the graph:

x

y

 And if we graph these points we see something like below (which is our answer).  Note that the dotted blue line is the vertical asymptote at .

Screen shot 2020 08 21 at 2.55.37 pm

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