CurriculumGrade 8Mathematics

Systems of Linear Equations

Aligned to 8.EE.C.8 — Common Core State Standards for Mathematics.

What this lesson teaches

A system is two lines; the solution is the point where they cross — the (x, y) that makes BOTH true. Substitution: solve one equation for a variable and plug it into the other.

Worked example

y = x + 1 and y = 2x − 3. Set equal: x + 1 = 2x − 3 → 4 = x. Then y = 4 + 1 = 5. Solution: (4, 5).

Practice questions

  1. Solve y = 3x and y = x + 4.
  2. Solve x + y = 10 and x − y = 2.
  3. Two lines are parallel. How many solutions does the system have?

Watch the lesson

Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.

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En español

Sistemas de Ecuaciones Lineales

Un sistema son dos rectas; la solución es el punto donde se cruzan — el par (x, y) que hace que AMBAS ecuaciones sean verdaderas. Sustitución: despeja una variable en una ecuación y sustitúyela en la otra.

Ejemplo: y = x + 1 e y = 2x − 3. Iguala: x + 1 = 2x − 3 → 4 = x. Luego y = 4 + 1 = 5. Solución: (4, 5).

More Expressions & Equations lessons

Slope & Linear Equations (y = mx + b)8.EE.B.6Exponents and Scientific Notation8.EE.A.1Square Roots & Cube Roots8.EE.A.2Scientific Notation & Magnitude8.EE.A.3Operations in Scientific Notation8.EE.A.4Proportional Relationships & Slope8.EE.B.5

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