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4.3.1. Unique Solution for Linear Equations
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Today we will explore linear equations in two variables and see how they differ from one-variable equations. Does anyone remember how many solutions a linear equation in one variable has?
Yes! It has a unique solution.
Exactly! Now, what do you think happens when we move to two variables?
Maybe it also has a unique solution?
Not quite! A linear equation in two variables can have infinitely many solutions. For instance, the equation 2x + 3y = 12 has multiple pairs of (x, y) that satisfy it.
Can you give an example of those pairs?
Sure! If we set x to 3, then y can be calculated as 2. So, (3, 2) is one solution. If x is 0, then we find another pair: (0, 4).
So there are many pairs that work?
Exactly! In fact, there's no limit to the number of solutions. Does that make sense?
Yes!
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Now let's see how we can find solutions for a linear equation systematically. Let's work with the equation x + 2y = 6. Who can find a solution?
If I set y to 0, then x must be 6!
Great! So, (6, 0) is indeed a solution. What if we let y equal 1?
That would make x equal to 4, giving us the pair (4, 1).
Exactly! And what happens if we set y to 3?
That would give us (0, 3)!
Right! So, we see how changing one variable affects the other, allowing us to find multiple solutions. Now let's practice finding pairs for the equation 2x + 3y = 12.
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Create a free accountLet’s discuss how to verify if a given pair, say (2, 4), is a solution for 2x + 3y = 12. How would you do it?
We can substitute x = 2 and y = 4 into the equation!
Correct! Let's do the math: What do we get?
That would be 2(2) + 3(4) = 4 + 12, which is 16.
That's not equal to 12. So, (2, 4) is not a solution. Let’s try (0, 4).
Substituting gives us 2(0) + 3(4) = 12. So (0, 4) is indeed a solution!
Exactly! This is how we check potential solutions. Remember to always substitute back into the original equation.
Overview
Short Summary
This section discusses how linear equations in two variables can have infinitely many solutions, contrasting them with unique solutions in one-variable equations.
Medium Summary
In this section, students learn that linear equations in two variables do not have a unique solution but rather an infinite number of solutions represented as pairs of values (x, y). The section emphasizes the identification and verification of solutions through examples.
Detailed Summary
Unique Solutions in Linear Equations
In this section, we explore the characteristics of linear equations with two variables, emphasizing that unlike linear equations in one variable, which have a unique solution, linear equations in two variables can have infinitely many solutions. A solution to such an equation is represented as an ordered pair (x, y) that satisfies the equation. For example, the equation 2x + 3y = 12 has solutions such as (3, 2), (0, 4), and even (6, 0). This is because by choosing different values for either variable, corresponding values can be calculated for the other variable.
Further, the section illustrates finding solutions through various approaches, including substituting values directly and validating whether given pairs are indeed solutions to the equations. A focus is laid on practical exercises and examples demonstrating how a single equation can yield multiple valid solutions, reflecting the richness and flexibility in handling two-variable linear equations.
Reference YouTube Videos
Audio Book
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Create a free accountYou have seen that every linear equation in one variable has a unique solution. What can you say about the solution of a linear equation involving two variables? As there are two variables in the equation, a solution means a pair of values, one for x and one for y which satisfy the given equation.
Detailed Explanation
In this chunk, we learn that while a linear equation in one variable has just one solution, a linear equation in two variables actually has multiple solutions. When we refer to 'solutions' here, we mean ordered pairs (x, y). Each pair represents a point on a Cartesian plane that satisfies the equation.
Examples & Analogies
Imagine you have a treasure map that shows a path to a treasure chest. If the line on the map represents a linear equation, then every spot along that line where you can dig represents a solution. Some spots may be better than others, but they all lead to the treasure.
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Create a free accountLet us consider the equation 2 x + 3y = 12. Here, x = 3 and y = 2 is a solution because when you substitute x = 3 and y = 2 in the equation above, you find that 2x + 3y =(2 × 3) + (3 × 2) = 12. This solution is written as an ordered pair (3, 2), first writing the value for x and then the value for y.
Detailed Explanation
In this example, we take a specific equation and demonstrate how to find solutions. By substituting values for x and y, you can check if they satisfy the equation. If they do, then that pair is a solution. The example illustrates the process of checking solutions, which is a key skill when working with equations.
Examples & Analogies
Think of this like baking a cake with a specific recipe. The ingredients (x and y) need to be combined in precise amounts (the equation) to yield a successful cake (a solution). If you get the measurements right (find the correct pairs), you'll enjoy a delicious cake.
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Create a free accountIn fact, we can get many many solutions in the following way. Pick a value of your choice for x (say x = 2) in 2 x + 3y = 12. Then the equation reduces to 4 + 3y = 12, which is a linear equation in one variable. On solving this, you get y = 8/3. So (2, 8/3) is another solution of 2 x + 3y = 12.
Detailed Explanation
This chunk shows that we can generate solutions for the equation by choosing any value for one variable and then calculating the other variable. This practice demonstrates that for every chosen x, there is a corresponding unique y, leading to infinitely many solutions.
Examples & Analogies
Imagine you're planning a road trip and can choose how far you want to drive (x). Depending on your destination, there's a unique time(to arrive, which represents y). The further you choose to drive, the longer you will need to travel, demonstrating how each choice in x leads to a specific outcome in y.
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Create a free accountSimilarly, choosing x = –5, you find that the equation becomes –10 + 3 y = 12. This gives y = 22/3. So, (–5, 22/3) is another solution of 2x + 3y = 12. So there is no end to different solutions of a linear equation in two variables. That is, a linear equation in two variables has infinitely many solutions.
Detailed Explanation
When we substitute a negative value for x and solve for y, we again find a different ordered pair that satisfies the equation. This illustrates that not only do we have various positive solutions, but negative values can also yield valid solutions, emphasizing the idea of infinite possibilities.
Examples & Analogies
Think about a playground where children can swing higher and higher (choosing different heights), and for each height, there are different ways to come down (different solutions). Just like how every swing’s height gives its own unique fun experience, every choice of x leads to a new y, showing their many options.
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Create a free accountExample 3 : Find four different solutions of the equation x + 2y = 6. By inspection, x = 2, y = 2 is a solution because for x = 2, y = 2 x + 2y = 2 + 4 = 6.
Detailed Explanation
Here we demonstrate finding multiple solutions for another equation by checking various combinations of x and y. The strategy of 'inspection' means you can quickly suggest pairs that work without needing to derive the equation each time.
Examples & Analogies
Consider a group project where multiple team members can take different roles to accomplish a single goal (the equation). Each member's choice (x or y) helps achieve the final objective, showing that many approaches can lead to the same outcome.
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Key Concepts
Core takeaways and short definitions to help you quickly recall the key ideas from this section.
Linear equations in two variables have infinitely many solutions.
Solutions are represented as ordered pairs (x, y).
Substituting values for one variable allows finding multiple corresponding values for the other variable.
Examples
Memory Aids
Interactive tools to help you remember key concepts