Math Problem Statement

Find the solution set of the given equations using elimination: 2x - 5y = -13; -3y + 4 = -5x

Solution

We are tasked with solving the system of equations using the elimination method:

  1. 2x5y=132x - 5y = -13 (Equation 1)\text{(Equation 1)}
  2. 3y+4=5x-3y + 4 = -5x (Equation 2)\text{(Equation 2)}

Step 1: Rearrange the second equation

To align both equations better, we need to rearrange Equation 2 into a form similar to Equation 1:

3y+4=5x-3y + 4 = -5x Add 5x5x to both sides: 5x3y=4(Equation 3)5x - 3y = 4 \quad \text{(Equation 3)}

Now, we have the system:

2x5y=13(Equation 1)2x - 5y = -13 \quad \text{(Equation 1)} 5x3y=4(Equation 3)5x - 3y = 4 \quad \text{(Equation 3)}

Step 2: Multiply to eliminate one variable

We will eliminate xx. To do that, let's multiply the first equation by 5 and the second equation by 2, so that the coefficients of xx will be the same:

Multiply Equation 1 by 5: (5)(2x5y)=5(13)10x25y=65(Equation 4)(5)(2x - 5y) = 5(-13) \quad \Rightarrow \quad 10x - 25y = -65 \quad \text{(Equation 4)}

Multiply Equation 3 by 2: (2)(5x3y)=(2)(4)10x6y=8(Equation 5)(2)(5x - 3y) = (2)(4) \quad \Rightarrow \quad 10x - 6y = 8 \quad \text{(Equation 5)}

Step 3: Subtract the equations

Now subtract Equation 5 from Equation 4 to eliminate xx:

(10x25y)(10x6y)=(65)(8)(10x - 25y) - (10x - 6y) = (-65) - (8) This simplifies to: 10x25y10x+6y=65810x - 25y - 10x + 6y = -65 - 8 19y=73-19y = -73 Solving for yy: y=7319=7319=3.84(rounded to 2 decimal places).y = \frac{-73}{-19} = \frac{73}{19} = 3.84 \quad \text{(rounded to 2 decimal places)}.

Step 4: Substitute yy back into one of the original equations

Let's substitute y=3.84y = 3.84 into Equation 1 to solve for xx:

2x5(3.84)=132x - 5(3.84) = -13 2x19.2=132x - 19.2 = -13 Add 19.2 to both sides: 2x=6.22x = 6.2 Solving for xx: x=6.22=3.1.x = \frac{6.2}{2} = 3.1.

Final Solution Set:

x=3.1,y=3.84.x = 3.1, \quad y = 3.84.

This is the solution set for the system of equations.

Would you like further details or clarifications on any steps?


Related Questions:

  1. How does the substitution method compare to elimination?
  2. Can you solve the same system graphically?
  3. What happens when a system of equations has no solution?
  4. How do you solve systems of three variables using elimination?
  5. What are other methods for solving systems of linear equations?

Tip: Always check your solution by substituting it back into the original equations.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
System of Equations
Elimination Method

Formulas

Linear equation: ax + by = c
Elimination method for solving systems of equations

Theorems

Properties of equality
Linear combination in elimination method

Suitable Grade Level

Grades 8-10