Math Problem Statement

Solve the system of equations using the elimination method: -3x + 3y = 15 -4x - 5y = -16

Solution

The given system of equations is:

3x+3y=15-3x + 3y = 15 4x5y=16-4x - 5y = -16

We will solve this system using the elimination method.


Step 1: Align the equations

Write the equations in the given form:

  1. 3x+3y=15-3x + 3y = 15
  2. 4x5y=16-4x - 5y = -16

Step 2: Eliminate one variable

To eliminate one variable, we aim to make the coefficients of either xx or yy equal in both equations. Here, we will eliminate yy.

Make the yy-coefficients equal:

  • Multiply the first equation by 55 and the second equation by 33: 5(3x+3y)=5(15)    15x+15y=755(-3x + 3y) = 5(15) \implies -15x + 15y = 75 3(4x5y)=3(16)    12x15y=483(-4x - 5y) = 3(-16) \implies -12x - 15y = -48

Now we have:

  1. 15x+15y=75-15x + 15y = 75
  2. 12x15y=48-12x - 15y = -48

Step 3: Add the equations

Add the two equations to eliminate yy: (15x+15y)+(12x15y)=75+(48)(-15x + 15y) + (-12x - 15y) = 75 + (-48) 15x12x=27-15x - 12x = 27 27x=27-27x = 27 Solve for xx: x=1x = -1


Step 4: Solve for yy

Substitute x=1x = -1 into one of the original equations. Using the first equation: 3x+3y=15-3x + 3y = 15 Substitute x=1x = -1: 3(1)+3y=15-3(-1) + 3y = 15 3+3y=153 + 3y = 15 3y=123y = 12 y=4y = 4


Final Solution:

The solution to the system of equations is: x=1,y=4x = -1, \, y = 4


Would you like a detailed explanation of a specific step?
Here are some related questions:

  1. How can we eliminate xx instead of yy?
  2. How does substitution compare to elimination in solving this system?
  3. Can this method solve non-linear systems of equations?
  4. What are other ways to check the solution's correctness?
  5. How does elimination work with three equations and three variables?

Tip: Always double-check your solution by substituting the values back into the original equations.

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Math Problem Analysis

Mathematical Concepts

Algebra
Systems of Linear Equations
Elimination Method

Formulas

Ax + By = C (Standard form of a linear equation)

Theorems

Properties of Equality (Addition/Subtraction)

Suitable Grade Level

Grades 9-11