Math Problem Statement

Solve the following system of equations for all three variables: 1. 6x + y - 5z = -6 2. -9x - y + 7z = 5 3. -5x - y + 3z = -7

Solution

To solve the given system of linear equations for xx, yy, and zz, we have:

  1. 6x+y5z=66x + y - 5z = -6
  2. 9xy+7z=5-9x - y + 7z = 5
  3. 5xy+3z=7-5x - y + 3z = -7

Step 1: Eliminate yy

Add the first and second equations to eliminate yy: (6x+y5z)+(9xy+7z)=6+5(6x + y - 5z) + (-9x - y + 7z) = -6 + 5 3x+2z=1(Equation 4)-3x + 2z = -1 \quad \text{(Equation 4)}

Add the first and third equations to eliminate yy: (6x+y5z)+(5xy+3z)=67(6x + y - 5z) + (-5x - y + 3z) = -6 - 7 x2z=13(Equation 5)x - 2z = -13 \quad \text{(Equation 5)}

Step 2: Solve the two-variable system

Now solve the two-variable system formed by Equation 4 and Equation 5:

  1. 3x+2z=1-3x + 2z = -1 (Equation 4)
  2. x2z=13x - 2z = -13 (Equation 5)

From Equation 5: x=13+2zx = -13 + 2z

Substitute x=13+2zx = -13 + 2z into Equation 4: 3(13+2z)+2z=1-3(-13 + 2z) + 2z = -1 396z+2z=139 - 6z + 2z = -1 394z=139 - 4z = -1 4z=40z=10-4z = -40 \quad \Rightarrow \quad z = 10

Substitute z=10z = 10 into x=13+2zx = -13 + 2z: x=13+2(10)=13+20=7x = -13 + 2(10) = -13 + 20 = 7

Step 3: Solve for yy

Substitute x=7x = 7 and z=10z = 10 into the first equation: 6(7)+y5(10)=66(7) + y - 5(10) = -6 42+y50=642 + y - 50 = -6 y8=6y - 8 = -6 y=2y = 2

Final Solution:

x=7,  y=2,  z=10x = 7, \; y = 2, \; z = 10

Let me know if you'd like detailed steps for verification or any further clarification.

Here are five follow-up questions you can explore:

  1. What is the determinant of the coefficient matrix of this system?
  2. Can this system be solved using matrix methods such as Gaussian elimination?
  3. How would the solution change if one of the equations is modified?
  4. What are some real-world applications of solving systems of equations like this?
  5. Can this problem be solved graphically?

Tip: Always double-check your substitutions when solving simultaneous equations to avoid minor arithmetic errors.

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Math Problem Analysis

Mathematical Concepts

Algebra
System of Linear Equations

Formulas

Elimination method
Substitution method

Theorems

Properties of linear equations

Suitable Grade Level

Grades 10-12