Algebra 1 : How to find the solution for a system of equations

Study concepts, example questions & explanations for Algebra 1

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Example Questions

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.

Example Question #21 : How To Find The Solution For A System Of Equations

If

and

Solve for  and .

Possible Answers:

None of the available answers

Correct answer:

Explanation:

rearranges to

and

, so

Example Question #1 : How To Find The Solution For A System Of Equations

Solve for  in the system of equations:

Possible Answers:

The system has no solution

Correct answer:

Explanation:

In the second equation, you can substitute  for  from the first.

Now, substitute 2 for  in the first equation:

 

The solution is 

Example Question #2 : How To Find The Solution For A System Of Equations

Without drawing a graph of either equation, find the point where the two lines intersect.

Line 1 : 

Line 2 : 

Possible Answers:

Correct answer:

Explanation:

To find the point where these two lines intersect, set the equations equal to each other, such that  is substituted with the  side of the second equation. Solving this new equation for  will give the -coordinate of the point of intersection.

Subtract from both sides.

Divide both sides by 2.

Now substitute  into either equation to find the -coordinate of the point of intersection.

With both coordinates, we know the point of intersection is . One can plug in  for  and  for  in both equations to verify that this is correct.

Example Question #3 : How To Find The Solution For A System Of Equations

What is the sum of and for the following system of equations?

Possible Answers:

Correct answer:

Explanation:

Add the equations together.

Put the terms together to see that .

Substitute this value into one of the original equaitons and solve for .

Now we know that , thus we can find the sum of and .

Example Question #294 : Equations / Inequalities

Two lines have equations of  and . At what point do these lines intersect?

Possible Answers:

Correct answer:

Explanation:

We can solve this problem by setting up a simple system of equations. First, we want to change the equations so one variable can cancel out. Multiplying the first equation by 2 and the second equation by 3 gives us a new system of  and . These equations add up to  or . Plugging in 7 for  in either of the original two equations shows us that  is equal to 1 and the point is .

Example Question #22 : How To Find The Solution For A System Of Equations

Does this system of equations have one solution, no solutions, or infinite solutions?

Possible Answers:

one solution:

no solution

one solution:

infinite solutions

Correct answer:

infinite solutions

Explanation:

This system has infinite solutions becasue the two equations are actually the exact same line. To discover this, put both equations in terms of y.

First, . Add y to both sides:

Now add 3 to both sides:

 

Now we can show that the second equation also represents the line

add 6 to both sides

divide both sides by 2

 

Since both equations are the same line, literally any point on one line will also be on the other - infinite solutions.

Example Question #23 : How To Find The Solution For A System Of Equations

Find the solution for the system of equations.

 and 

Possible Answers:

 and 

 and 

 and 

 and 

 and 

Correct answer:

 and 

Explanation:

A system of equations can be solved by subsituting one variable for another. Since we know that , we can subsitute this into the other equation so . This expression can be solved to find that . Now that we know the value of  it can be subsituted into either of the original equations to find .

Example Question #61 : Equations / Solution Sets

Possible Answers:

Correct answer:

Explanation:

Example Question #22 : How To Find The Solution For A System Of Equations

Determine the intersection point of the following two equations.

Possible Answers:

Correct answer:

Explanation:

To find the intersection point, you must find the values of x and y that satisfy the two equations. We can use the method of adding the two equations together:

If we add the equations together, the y terms cancel out, so we get

Now that we know the value of x, we can plug that into one of the equations and solve for y. Pluggin it into the first equation, we get

.

So that point of intersection is , or .

 

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