Chapter 6: Problem 41
\(\begin{aligned} 2 x-y+2 z &=6 \\ -x+y+z &=0 \\ -x-3 z &=-6 \end{aligned}\)
Short Answer
Expert verified
The solution is \(x = 6\), \(y = 6\), \(z = 0\).
Step by step solution
01
Solve for x from equation 3
Start by considering the third equation \(-x - 3z = -6\). To solve for \(x\), rearrange the terms to get \(x = 3z + 6\). We will use this expression for \(x\) in the other equations.
02
Substitute x in equations 1 and 2
Substitute \(x = 3z + 6\) into the first equation: \(2x - y + 2z = 6\), which becomes \(2(3z + 6) - y + 2z = 6\) or \(6z + 12 - y + 2z = 6\). Simplify it to \(8z - y = -6\) or \(y = 8z + 6\).Next, substitute \(x = 3z + 6\) into the second equation: \(-x + y + z = 0\), which becomes \(-(3z + 6) + y + z = 0\) or \(-3z - 6 + y + z = 0\). Simplify it to \(y - 2z = 6\) or \(y = 2z + 6\).
03
Equate expressions for y
We have two expressions for \(y\): \(y = 8z + 6\) and \(y = 2z + 6\). Equate these two expressions: \(8z + 6 = 2z + 6\). Solve for \(z\) by subtracting \(2z\) from both sides to get \(6z = 0\), giving \(z = 0\).
04
Substitute back to find y and x
Use \(z = 0\) in \(y = 2z + 6\) to find \(y\). Substituting \(z = 0\) gives \(y = 6\).Next, use \(z = 0\) in \(x = 3z + 6\) to find \(x\). Substituting \(z = 0\) gives \(x = 6\).
05
Verify the solution
Verify the solution by substituting \(x = 6\), \(y = 6\), and \(z = 0\) back into the original equations.1. For \(2x - y + 2z = 6\): Substitute to get \(2(6) - 6 + 2(0) = 12 - 6 = 6\), which matches.2. For \(-x + y + z = 0\): Substitute to get \(-6 + 6 + 0 = 0\), which matches.3. For \(-x - 3z = -6\): Substitute to get \(-6 - 3(0) = -6\), which matches.All equations are satisfied, confirming the solution is correct.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Linear Equations
Linear equations are mathematical expressions that create a straight line when graphed on a coordinate plane. They consist of variables and constants with linear relationships. In this problem, we have three linear equations:
- \(-x - 3z = -6\)
- \(-x + y + z = 0\)
- \(2x - y + 2z = 6\)
Substitution Method
The substitution method is a technique used to solve systems of equations, particularly effective for systems like linear ones. Here’s how it is applied in our problem:Start by solving one of the equations for a specific variable. For instance, from the third equation, solve for \(x\):
- Equation: \(-x - 3z = -6\)
- Rearrange to find \(x\): \(x = 3z + 6\)
- Substitute \(x = 3z + 6\) into the first equation: \(2(3z + 6) - y + 2z = 6\)
- This simplifies to: \(8z - y = -6\) or \(y = 8z + 6\)
- Also, substitute \(x = 3z + 6\) into the second equation: \(-3z - 6 + y + z = 0\)
- Simplifying it yields: \(y = 2z + 6\)
Verification of Solutions
Verifying solutions is the final step in solving systems of equations. It confirms that the solutions satisfy all given equations.For this problem, once we found \(x = 6\), \(y = 6\), and \(z = 0\), we need to substitute these values back into the original equations to verify:
- Substitute into \(2x - y + 2z = 6\):
\(2(6) - 6 + 2(0) = 12 - 6 = 6\)
This equation is satisfied. - Check \(-x + y + z = 0\):
\(-6 + 6 + 0 = 0\)
This equation checks out as well. - Confirm with \(-x - 3z = -6\):
\(-6 - 3(0) = -6\)
Matched exactly.