Mathematics
Grade 8
15 min
Is (x, y) a solution to the system of equations?
Is (x, y) a solution to the system of equations?
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Introduction & Learning Objectives
Learning Objectives
Define what a solution to a single linear equation represents.
Define what a solution to a system of linear equations represents.
Accurately substitute the x and y values from an ordered pair into a linear equation.
Determine if a given ordered pair (x, y) satisfies a single linear equation.
Determine if a given ordered pair (x, y) satisfies *all* equations in a system of linear equations.
Explain why a point must satisfy every equation to be considered a solution to the entire system.
Ever wonder if a secret code works for *all* parts of a message? 🕵️♀️ In math, we'll learn how to check if a single point works for *all* equations in a system!
This lesson will teach you how to verify if a specific point (x, y) is a solution to a system of linear eq...
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Key Concepts & Vocabulary
TermDefinitionExample
Linear EquationAn equation whose graph is a straight line. It typically involves two variables, like x and y, and no variable is raised to a power higher than 1.$2x + y = 5$
Ordered Pair (x, y)A pair of numbers written in a specific order, usually representing a point on a coordinate plane. The first number is the x-coordinate, and the second is the y-coordinate.$(3, -1)$ where $x=3$ and $y=-1$
Solution to a Single EquationAn ordered pair (x, y) that makes the equation true when its values are substituted for the variables.For $x + y = 7$, the point $(3, 4)$ is a solution because $3 + 4 = 7$ is true.
System of Linear EquationsTwo or more linear equations that are considered together. We are looking for a solution that satisfies *all* of them at the same time.$\{ \beg...
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Core Formulas
Rule for Checking a Single Linear Equation
Given an equation $Ax + By = C$ and an ordered pair $(x_0, y_0)$, substitute $x_0$ for $x$ and $y_0$ for $y$. If $A(x_0) + B(y_0) = C$ is a true statement, then $(x_0, y_0)$ is a solution to that equation.
Use this rule to determine if a point lies on the line represented by a single equation. The goal is to see if the left side of the equation equals the right side after substitution.
Rule for Checking a System of Linear Equations
Given a system of equations and an ordered pair $(x_0, y_0)$, substitute $x_0$ for $x$ and $y_0$ for $y$ into *each* equation in the system. If $(x_0, y_0)$ makes *all* equations true, then it is a solution to the system. If it makes even one equation false, it is NOT a solution to the system.
This is the...
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Challenging
A student claims (1, 4) is a solution to the system {y = 3x + 1, 2x + y = 5}. Their work is shown below. Where is the mistake?
Step 1: Check Eq 1: 4 = 3(1) + 1 -> 4 = 4. (Correct)
Step 2: Check Eq 2: 2(1) + 4 = 5
Step 3: Simplify: 6 = 5. (Incorrect)
Step 4: Conclusion: It is a solution.
A.The mistake is in Step 1; the calculation is wrong.
B.The mistake is in Step 4; a point that fails any equation is not a solution.
C.The mistake is in Step 2; the substitution is wrong.
D.There is no mistake; the point is a solution.
Challenging
For what value of 'k' is the ordered pair (3, 1) a solution to the system of equations?
Equation 1: x - y = 2
Equation 2: kx + 2y = 11
A.k = 3
B.k = 2
C.k = 1
D.k = 4
Challenging
The point (2, 1) is a solution to the system: {Ax + By = 5, Ax - By = 3}. What is the value of A?
A.= 1
B.= 4
C.= 2
D.= 5
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