Algebra 1 : Systems of Equations

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #161 : Systems Of Equations

Solve for :

Possible Answers:

Correct answer:

Explanation:

First, combine like terms to get .

Then, subtract 3 and  from both sides to get .

Then, divide both sides by 2 to get a solution of .

Example Question #42 : Equations / Solution Sets

Solve this system of equations: 

Possible Answers:

Correct answer:

Explanation:

To solve this system of equations, the elimination method can be used (the  terms cross out).

Once you eliminate the , you have .

Then isolate for , and you get .

Plug into the first equation to solve for .

Example Question #162 : Systems Of Equations

Solve the following system of equations:

Possible Answers:

This system has no solution.

This system has an infinite number of solutions.

Correct answer:

This system has an infinite number of solutions.

Explanation:

Rearrange the second equation:

This is just a multiple of the first equation (by a factor of 3).  Therefore, the two equations are dependent on each are and are going to have an infinite number of solutions.

Example Question #1 : Solve Systems Of Two Linear Equations: Ccss.Math.Content.8.Ee.C.8b

Solve the set of equations:

Possible Answers:

Correct answer:

Explanation:

Solve the first equation for :

Substitute into the second equation:

Multiply the entire equation by 2 to eliminate the fraction:

Using the value of , solve for :

Therefore, the solution is

Example Question #2 : Systems Of Equations

Find the solution:

Possible Answers:

Correct answer:

Explanation:

To solve this system of equations, we must first eliminate one of the variables. We will begin by eliminating the  variables by finding the least common multiple of the  variable's coefficients.  The least common multiple of 3 and 2 is 6, so we will multiply each equation in the system by the corresponding number, like

.

By using the distributive property, we will end up with

Now, add down each column so that you have

Then you solve for  and determine that .

But you're not done yet!  To find , you have to plug your answer for  back into one of the original equations:

Solve, and you will find that .  

Example Question #2 : Solve Systems Of Two Linear Equations: Ccss.Math.Content.8.Ee.C.8b

Solve the following system of equations:

Possible Answers:

Correct answer:

Explanation:

Set the two equations equal to one another:

2x - 2 = 3x + 6

Solve for x:

x = -8

Plug this value of x into either equation to solve for y.  We'll use the top equation, but either will work.

y = 2 * (-8) - 2

y = -18

Example Question #163 : Systems Of Equations

Solve the following system of equations:

Possible Answers:

Correct answer:

Explanation:

Solve the second equation for y:

x - 2y = 4

-2y = 4 - x

y = -2 + x/2

Plug this into the first equation:

3x + 2(-2 + x/2) = 8

Solve for x:

3x - 4 + x = 8

4x = 12

x = 3

Plug this into the second equation to get a value for y:

3 - 2y = 4

2y = -1

y = -0.5

Example Question #164 : Systems Of Equations

Solve the following system of equation

Possible Answers:

Cannot be solved

Correct answer:

Explanation:

Start with the equation with the fewest variables, .

Solve for by dividing both sides of the equaion by 6:

Plug this  value into the second equation to solve for :

Subtract 10 from both sides:

Divide by 9:

Plug these and values into the first equation to find :

Combine like terms:

Subtract 2:

Divide by -4:

Therefore the final solution is .

Example Question #165 : Systems Of Equations

Two integers,  and , sum to 16, but when  is doubled, they sum to 34. Find  and .

Possible Answers:

No solution

Correct answer:

Explanation:

 and  add up to 16:

When  is doubled to , they sum to 34:

We have two equations and two unknowns, so we can find a solution to this system.

Solve for in the first equation:

Plug this into the second equation:

Solve for :

Use this  value to find . We already have a very simple equation for , .

Therefore the answer is .

Example Question #261 : Equations / Inequalities

Solve for .

Possible Answers:

Correct answer:

Explanation:

For the second equation, solve for  in terms of .

Plug this value of y into the first equation.

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