Chapter 6: Problem 22
Solve each system by substitution. $$\begin{aligned}&2 x+6 y=-18\\\&5 y=-29+3 x\end{aligned}$$
Short Answer
Expert verified
The solution is \(x = -\frac{66}{7}\), \(y = \frac{1}{7}\).
Step by step solution
01
Solve One Equation for a Variable
We will first solve the second equation for one of the variables. Let's solve the second equation, \(5y = -29 + 3x\), for \(y\). We'll isolate \(y\) by adding 29 to both sides and then dividing by 5. This gives us:\[y = \frac{3x + 29}{5}\]
02
Substitute Expression in the Other Equation
Now that we have \(y\) in terms of \(x\), we'll substitute this expression into the first equation, \(2x + 6y = -18\). Substituting gives us:\[2x + 6\left(\frac{3x + 29}{5}\right) = -18\]
03
Solve for x
Simplify the equation to find \(x\).First, distribute the 6:\[2x + \frac{18x + 174}{5} = -18\]To eliminate the fraction, multiply every term by 5:\[10x + 18x + 174 = -90\]Combine like terms:\[28x + 174 = -90\]Subtract 174 from both sides:\[28x = -264\]Finally, divide by 28:\[x = -\frac{264}{28} = -\frac{66}{7}\]
04
Substitute x Back to Find y
Using the value of \(x\) we found, substitute back into the expression for \(y\):\[y = \frac{3\left(-\frac{66}{7}\right) + 29}{5}\]\[y = \frac{-\frac{198}{7} + \frac{203}{7}}{5}\]\[y = \frac{\frac{5}{7}}{5}\]\[y = \frac{1}{7}\]
05
Conclusion
We found that the solution to the system of equations is \(x = -\frac{66}{7}\) and \(y = \frac{1}{7}\). These values satisfy both equations.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Substitution Method
The substitution method is a powerful technique for solving systems of equations, where we express one variable in terms of another and substitute it into the other equation. This reduces the system to a single equation, allowing us to solve for the unknowns step by step. In the given problem, the method begins by transforming the second equation into a simpler form. We started with the equation:
- \(5y = -29 + 3x\)
- \(y = \frac{3x + 29}{5}\)
Linear Equations
Linear equations are fundamental algebraic expressions where each term is either a constant or the product of a constant and a single variable. The instructors in our exercise exemplified this with two linear equations:
- \(2x + 6y = -18\)
- \(5y = -29 + 3x\)
Algebraic Expressions
Algebraic expressions are combinations of numbers, operations, and variables. They form the basis of equations and inequalities in mathematics. In our exercise, an algebraic expression such as \(5y = -29 + 3x\) neatly encapsulates relationships between variables \(x\) and \(y\). By manipulating these expressions, we solve for the unknowns within them. We turned the equation into the expression:
- \(y = \frac{3x + 29}{5}\).