Linear Equations Through Two Points

Multiple Choice

ACT Practice Warm-Up:

Which of the following equations matches the given graphed linear equation?

• $$y=-\frac{2}{3}x+5$$

• $$y=-\frac{3}{2}x+5$$

• $$y=\frac{2}{3}x-5$$

• $$y=\frac{3}{2}x-5$$

Unit 2 Lesson 1b:
Slope Intercept Equations From Two Points

Concept:

Slope Formula

Multiple Choice

Which of the following is slope formula?

• $$\frac{y-y}{x-x}=m$$

• $$\frac{x-y}{x-y}=m$$

• $$\frac{x-x}{y-y}=m$$

• $$y=mx+b$$

Procedure:

1) Identify two points.
2) Substitute the (x, y) of each point into the slope formula.
3) Evaluate to get slope "m".
4) Substitute the slope and one of the (x, y) points into y = mx + b.
5) Evaluate to get the y-intercept "b".
6) Write the linear equation with values for "m" and "b".

​Example 1:

Write the equation through: (1, 4) & (-1, -2)

​Example 2:

Write the equation through: (2, 7) & (-1, -5)

​Example 3:

Write the equation through: (x, -2) & (2, 8); slope: 5