Mathematics
Grade 11
15 min
Solve a system of equations using any method
Solve a system of equations using any method
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1
Introduction & Learning Objectives
Learning Objectives
Identify the most efficient method (substitution, elimination, or matrix methods) for solving a given system of equations.
Solve systems of two and three linear equations using the elimination and substitution methods.
Solve systems of two linear equations using matrix-based methods, specifically Cramer's Rule.
Solve systems of equations involving one linear and one non-linear equation (e.g., a line and a parabola).
Interpret the nature of a system's solution (unique, infinite, or no solution) both algebraically and geometrically.
Verify the solution to any system by substituting the values back into the original equations.
How does an airplane's navigation system determine its precise location and speed? ✈️ It solves a complex system of eq...
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Key Concepts & Vocabulary
TermDefinitionExample
System of EquationsA collection of two or more equations that share the same set of variables. A solution to the system is a set of values for the variables that makes all equations in the system true simultaneously.The set of equations { 2x + y = 5, x - y = 1 } is a system. The solution is x=2, y=1 because these values satisfy both equations.
Consistent SystemA system of equations that has at least one solution. It can be 'independent' (exactly one solution) or 'dependent' (infinitely many solutions).The system { x + y = 2, 2x + 2y = 4 } is dependent and consistent because the second equation is just a multiple of the first. Any point on the line x+y=2 is a solution.
Inconsistent SystemA system of equations that has no solution. Geometrically, th...
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Core Formulas
Cramer's Rule (2x2 System)
For a system `ax + by = e` and `cx + dy = f`, the solution is given by: `x = D_x / D` and `y = D_y / D`, where `D = ad - bc ≠ 0`.
This formula provides a direct method for solving a 2x2 linear system using determinants. `D` is the determinant of the coefficient matrix, `D_x` is the determinant where the x-column is replaced by the constants, and `D_y` is the determinant where the y-column is replaced by the constants. LaTeX: `x = \frac{\begin{vmatrix} e & b \\ f & d \end{vmatrix}}{\begin{vmatrix} a & b \\ c & d \end{vmatrix}}`, `y = \frac{\begin{vmatrix} a & e \\ c & f \end{vmatrix}}{\begin{vmatrix} a & b \\ c & d \end{vmatrix}}`
Matrix Equation Form
A system can be written as `AX = B`. If the inverse matrix `A⁻¹`...
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Challenging
Find all points of intersection for the system `y = x²` and `x² + (y - 2)² = 4`.
A.(0, 0), (√3, 3), (-√3, 3)
B.(0, 0) only
C.(2, 4), (-2, 4)
D.(0, 0), (1, 1), (-1, 1)
Challenging
Which of the following systems is a dependent (infinitely many solutions) system that includes the point (4, -1) as one of its solutions?
A.x + y = 3 and 2x + 2y = 3
B.x - 4y = 8 and 2x - 8y = 10
C.x + 2y = 2 and 3x + 6y = 8
D.x - 4y = 8 and 2x - 8y = 16
Challenging
Consider the system: `x + y + z = 1`, `x + ky + z = 1`, `x + y + kz = 1`. For which value(s) of 'k' does the system NOT have a unique solution?
A.k = 0
B.k = 1
C.k = -1
D.k = 2
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