Algebra 1 : Systems of Equations

Study concepts, example questions & explanations for Algebra 1

varsity tutors app store varsity tutors android store

Example Questions

Example Question #2 : How To Find The Solution To A Rational Equation With Lcd

Solve for :

Possible Answers:

Correct answer:

Explanation:

Since the two fractions already have a common denominator, you can add the fractions by adding up the two numerators and keeping the common denominator:

Next you will algebraically solve for  by isolating it on one side of the equation. The first step is to multiply each side by :

Cancel out the  on the left and distribute out on the right. Then solve for  by subtracting  to the left and subtracting 10 to the right. Finally divide each side by negative 2:

Example Question #1 : How To Find The Solution To A Rational Equation With Lcd

Solve the rational equation:

Possible Answers:

no solution;  is extraneous

Correct answer:

Explanation:

With rational equations we must first note the domain, which is all real numbers except . (If , then the term  will be undefined.) Next, the least common denominator is , so we multiply every term by the LCD in order to cancel out the denominators. The resulting equation is . Subtract  on both sides of the equation to collect all variables on one side: . Lastly, divide by the constant to isolate the variable, and the answer is . Be sure to double check that the solution is in the domain of our equation, which it is. 

Example Question #4 : How To Find The Solution To A Rational Equation With Lcd

Solve the rational equation:

Possible Answers:

 or 

 or 

no solution

Correct answer:

 or 

Explanation:

With rational equations we must first note the domain, which is all real numbers except . (Recall, the denominator cannot equal zero. Thus, to find the domain set each denominator equal to zero and solve for what the variable cannot be.) 

The least common denominator or  and  is . Multiply every term by the LCD to cancel out the denominators. The equation reduces to . We can FOIL to expand the equation to . Combine like terms and solve: . Factor the quadratic and set each factor equal to zero to obtain the solution, which is  or . These answers are valid because they are in the domain. 

Example Question #1 : How To Find The Solution To A Rational Equation With Lcd

Solve this rational equation: 

Possible Answers:

Correct answer:

Explanation:

There are two ways to solve this problem using LCD (Least Common Denominator). The first method requires that you convert all denominators to the LCD by multiplying appropriately, and then follow the operations the equation requests. The second method allows you to cancel out terms using the LCD by mutiplying each term by the LCD. This is the method used for this problem and sometimes the simpler method since it tends to eliminate some of the fractions.

Find the LCD:

The LCD will be based of the denominator of the first fraction (with 8 in the numerator). The middle term, based on this, is missing an x while the third term is missing . Our LCD will be  since it has all the parts of each denominator. Multiply each term by this LCD.

Cancel terms that are present in our denominators and the LCD (same terms) we are multiplying by (red numbers will be canceled out):

Rewrite equation:

Distribute the right side of the equation:

Move x's to one side:

completely isolate x:

           

 

 

Example Question #8 : How To Find The Solution To A Rational Equation With Lcd

Simplify the following expression:

Possible Answers:

Correct answer:

Explanation:

In order to simplify this problem, we are going to need to factor the ploynimials and then get the two terms to have the same denominator.

Starting out with factoring:

the x's on the right term cancel:

factoring one more time:

Now we need to make the denominators on both terms the same. Let's start by multiplying the left term by (x+2)/(x+2): 

**Note: We can do this because (x+2)/(x+2)=1 and multiplying something by 1 does not change its value

 

Now let's multiply the right term by (x-2)/(x-2):

 

Now the only difference in the denominators is the 2 on the right term. Let's multipl the left term by 2/2 in order to solve this:

Our denominators are finally the same! Let's combine the fractions:

Now let's distribute and combine like terms (we are almost done):

This expression can't be simplified any further. We have our answer!

 

 

Example Question #9 : How To Find The Solution To A Rational Equation With Lcd

Solve the equation: 

Possible Answers:

None of the other answers.

Correct answer:

Explanation:

Find a common denominator:

Subtract the fractions and multiply to cancel the denominator:

Move over the constant and isolate x:

Example Question #161 : Equations / Inequalities

Find the solution: 

Possible Answers:

None of these

Correct answer:

Explanation:

Multiply both sides by 2x:

Move all terms to one side:

Solve the quadratic:

Example Question #1 : How To Find Out When An Equation Has No Solution

Solve the rational equation:

Possible Answers:

no solution

 or 

Correct answer:

no solution

Explanation:

With rational equations we must first note the domain, which is all real numbers except  and . That is, these are the values of  that will cause the equation to be undefined. Since the least common denominator of , and  is , we can mulitply each term by the LCD to cancel out the denominators and reduce the equation to . Combining like terms, we end up with . Dividing both sides of the equation by the constant, we obtain an answer of . However, this solution is NOT in the domain. Thus, there is NO SOLUTION because  is an extraneous answer. 

Example Question #2 : How To Find Out When An Equation Has No Solution

Find the solution set:

Possible Answers:

None of the other answers.

Correct answer:

None of the other answers.

Explanation:

Use the substitution method to solve for the solution set.

1) 

2) 

Solve equation 2 for y:

Substitute into equation 1:

If equation 1 was solved for a variable and then substituted into the second equation a similar result would be found. This is because these two equations have No solution. Change both equations into slope-intercept form and graph to visualize. These lines are parallel; they cannot intersect. 

*Any method of finding the solution to this system of equations will result in a no solution answer.

Example Question #1 : How To Find Out When An Equation Has No Solution

How many solutions does the equation below have?

Possible Answers:

Infinite 

Two

One

No solutions

Three

Correct answer:

No solutions

Explanation:

When finding how many solutions an equation has you need to look at the constants and coefficients.

The coefficients are the numbers alongside the variables.

The constants are the numbers alone with no variables.

If the coefficients are the same on both sides then the sides will not equal, therefore no solutions will occur.

Use distributive property on the right side first.

           

No solutions

Learning Tools by Varsity Tutors