Math Problem Statement

Solve using elimination.

–3x + y = –14 2x − y = 7

Solution

Let's solve the system of equations using the elimination method.

We have the system:

  1. 3x+y=14-3x + y = -14
  2. 2xy=72x - y = 7

Step 1: Add the two equations

The goal is to eliminate one of the variables by adding or subtracting the equations. Notice that the yy-terms are opposite in sign (one is +y+y and the other is y-y), so if we add the two equations, the yy-terms will cancel out.

Add the two equations:

(3x+y)+(2xy)=14+7(-3x + y) + (2x - y) = -14 + 7

This simplifies to:

3x+2x+yy=7-3x + 2x + y - y = -7 x=7-x = -7

Step 2: Solve for xx

Now, solve for xx:

x=7x = 7

Step 3: Substitute x=7x = 7 into one of the original equations

We can substitute x=7x = 7 into either equation. Let's use the first equation:

3x+y=14-3x + y = -14 3(7)+y=14-3(7) + y = -14 21+y=14-21 + y = -14

Now, solve for yy:

y=14+21y = -14 + 21 y=7y = 7

Final Solution:

The solution to the system is:

x=7,y=7x = 7, \quad y = 7

Would you like any further details or clarifications on this? Here are some additional questions you can explore:

  1. How do you know when to use elimination versus substitution?
  2. What if both variables had the same coefficient in front of them?
  3. Can the elimination method be used for systems of three equations?
  4. How would this problem look if the equations were in a different format (e.g., fractions)?
  5. What are some common mistakes made during the elimination process?

Tip: Always check your solution by substituting the values of xx and yy back into the original equations to verify they satisfy both equations!

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Elimination Method

Formulas

Elimination Method: Adding or subtracting equations to eliminate variables

Theorems

Elimination Method for Solving Systems of Equations

Suitable Grade Level

Grades 7-9