8th Grade Illustrative Mathematics: Grade 8; Unit 4; Lesson 14: Practice Problem 4 (long version)

This longer version has detail on switching between the STANDARD form of an equation and the SLOPE-INTERCEPT form of the same equation. It is useful to understand how the coefficients (A and B) in the standard form contribute to the slope, i.e., begin with the standard form and algebraically isolate y (y = mx + b). Note why the slope is the opposite of A (-A) divided by B. Likewise, understand why the y-intercept is C divided by B.

There is also a bit more detail on the slope of the graphs, the solution to the system of equations, and the infinite number of solutions to a different system of equations. Observe how the change in slope changes the graph. Also, observe how changing B slides the graph along the y axis.

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Illustrative Mathematics
Unit 4: Linear Equations and Linear Systems
Lesson 14: Solving More Systems
Practice Problem #4

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