How to Solve for y in the Equation 3x + 2y = 6: A Step-by-Step Guide
The equation 3x + 2y = 6 is a linear equation in two variables, and solving for y means expressing y in terms of x. Here's the thing — this process is foundational in algebra and helps in graphing linear equations, analyzing relationships between variables, and solving systems of equations. Whether you’re a student learning algebra basics or someone brushing up on math skills, this guide will walk you through the steps to isolate y and understand the underlying principles Not complicated — just consistent. But it adds up..
Understanding the Goal
When solving for y in 3x + 2y = 6, the objective is to rearrange the equation so that y is alone on one side of the equation. This results in an expression of the form y = mx + b, where m is the slope and b is the y-intercept. This form is essential for graphing the equation or analyzing how y changes with respect to x Worth knowing..
Step-by-Step Solution
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Start with the original equation:
3x + 2y = 6 -
Subtract 3x from both sides:
To isolate the term with y, eliminate 3x by subtracting it from both sides:
2y = 6 - 3x -
Divide both sides by 2:
Now, divide every term by 2 to solve for y:
y = (6 - 3x)/2 -
Simplify the expression:
Break down the numerator and simplify:
y = (6/2) - (3x/2)
y = 3 - (3/2)xRearranged, this becomes:
y = - (3/2)x + 3
This is the slope-intercept form, where the slope (m) is -3/2 and the y-intercept (b) is 3 Not complicated — just consistent..
Scientific Explanation
The process of solving for y relies on the properties of equality, which see to it that performing the same operation on both sides of an equation maintains balance. Subtracting 3x and dividing by 2 are inverse operations that systematically isolate y. This method is rooted in the principles of algebra, where variables are treated as unknown quantities to be determined through logical manipulation.
The slope-intercept form (y = mx + b) is particularly useful because it directly reveals the rate of change (slope) and the starting value (y-intercept) of the linear relationship. For the equation y = - (3/2)x + 3, the negative slope indicates that y decreases by 1.5 units for every 1 unit increase in x, and the y-intercept shows that the line crosses the y-axis at (0, 3).
Example Problem
Let’s apply the solution to a real-world scenario. Suppose a taxi service charges a flat fee of $3 plus $1.50 per mile. The total cost (y) can be modeled by the equation y = - (3/2)x + 3, where x represents the number of miles driven. Here, the negative slope might seem counterintuitive, but in this context, it could represent a discount applied per mile after a certain threshold Most people skip this — try not to..
To give you an idea, if x = 2 miles:
y = - (3/2)(2) + 3 = -3 + 3 = 0.
This suggests a hypothetical scenario where the discount equals the base fee after 2 miles, resulting in a net cost of $0 Not complicated — just consistent..
Common Mistakes to Avoid
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Forgetting to divide all terms by 2:
After subtracting 3x, ensure both 6 and -3x are divided by 2.
Incorrect: y = 6 - 3x
Correct: y = (6 - 3x)/2 -
Incorrectly simplifying fractions:
6/2 simplifies to 3, and -3x/2 remains as - (3/2)x Took long enough.. -
Misinterpreting the slope:
A negative slope means y decreases as x increases, which is crucial for graphing and real-world interpretation.
FAQ About Solving for y
Q: Why do we subtract 3x first?
A: To isolate the term with y, we eliminate 3x using inverse operations. This step ensures y is the only variable on one side of the equation.
Q: How do I check my solution?
A: Substitute the expression for y back into the original equation. Take this: if y = - (3/2)x + 3, plug it into 3x + 2y = 6 to verify both sides equal 6 Which is the point..
Q: What if the equation has fractions?
A: Multiply through by the denominator to eliminate fractions before isolating y. Here's one way to look at it: in ** (1/2)x + (1/3)y = 4**, multiply all terms by 6 to get 3x + 2y = 24, then solve for y Nothing fancy..
Q: Can this method be used for other linear equations?
A: Yes! The same steps apply to any linear equation: isolate the y-term, then divide by its coefficient to solve for y That alone is useful..
Conclusion
Solving for y in 3x + 2y = 6 involves isolating y through subtraction and division, resulting in the slope-intercept form y = - (3/2)x + 3. This process not only helps in graphing linear equations but also in understanding how variables interact in real-world scenarios. By mastering these steps, you build a foundation for tackling more complex algebraic problems, from systems of equations to quadratic functions. Remember to always check your work and apply the principles of equality to maintain accuracy. With practice, solving for variables becomes a logical and intuitive skill That's the part that actually makes a difference..
Extending the Concept: Applications Beyond Single Equations
The skills developed in solving for y extend naturally to more complex mathematical scenarios. When dealing with systems of linear equations, the ability to manipulate and isolate variables becomes essential for finding intersection points and analyzing multiple constraints simultaneously.
Consider a scenario where two cost models need to be compared:
- Model A: 3x + 2y = 6
- Model B: x - y = 2
By solving each equation for y, you can easily graph both lines and identify their point of intersection, which represents the break-even point where both models yield equal costs. This analytical approach is fundamental in economics, engineering optimization, and business decision-making And it works..
Graphical Interpretation and Slope Analysis
Understanding the slope-intercept form y = mx + b provides powerful insights into the behavior of linear relationships. Also, in our equation y = - (3/2)x + 3, the slope of -3/2 indicates that for every 2-unit increase in x, y decreases by 3 units. This rate of change is constant, creating a straight line when graphed That alone is useful..
When plotting this equation:
- The y-intercept occurs at (0, 3)
- Using the slope, another point would be (2, 0)
- Connecting these points gives the visual representation of all possible solutions
Practice Problems for Mastery
To solidify your understanding, try solving these variations:
- Basic Application: Solve for y in 4x - 3y = 12
- Fractional Coefficients: Rearrange ** (2/3)x + (1/4)y = 2** to slope-intercept form
- Real-world Scenario: A phone plan charges $20 monthly plus $0.10 per text. Write the cost equation and solve for total cost in terms of number of texts.
Technology Integration
Modern graphing calculators and software like Desmos or GeoGebra can verify your algebraic solutions. Inputting 3x + 2y = 6 directly will display the same line as y = - (3/2)x + 3, confirming your work while providing dynamic visualization of how changes in coefficients affect the graph's steepness and position.
Final Thoughts
Mastering the technique of isolating variables and converting to slope-intercept form opens doors to advanced mathematical thinking. Think about it: whether analyzing supply and demand curves, calculating rates of change in physics, or optimizing resources in operations research, these foundational skills remain indispensable. The key is recognizing that mathematics is not just about finding answers, but about understanding relationships and patterns that govern our world.
Remember that every complex problem begins with simple, well-executed steps. By maintaining precision in basic algebraic manipulations and developing intuition for what equations represent graphically, you equip yourself with tools that extend far beyond the classroom into practical problem-solving across all disciplines.