Chapter 4 Review

Chapter 4 Review

writing ​equations of lines

By Gianna Attardi

When given slope and y-intercept...

​Use y=mx+b

Replace the m with the slope, and the b with the y-intercept.

Multiple Choice

Write the slope-intercept form of the equation of the line given the slope and y-intercept.

$$Slope=-\frac{4}{5},\ y-intercept=-3$$  

• $$y=-3x-\frac{4}{5}$$  

• $$\frac{4}{5}x+y=-3$$  

• $$y=-\frac{4}{5}x-3$$  

• $$y=\frac{4}{5}x+3$$  

Multiple Choice

Write the slope-intercept form of the equation of the line given the slope and y-intercept.

$$Slope=-2,\ y-intercept=8$$  

• $$y=-2x+8$$  

• $$y=8x-2$$  

• $$2x+y=8$$  

• $$y=2x-8$$  

When given slope and a point...

​Use point-slope form: y-y₁=m(x-x₁)

Replace the m with the slope, and (x_1, y₁) with the given point.

Multiple Choice

Write the slope-intercept form of the equation of the line through (1, 2) with slope 7.

Step 1: Plug values into point-slope form. Choose the correct equation.

• $$y-1=7\left(x-2\right)$$  

• $$y-2=7\left(x-1\right)$$  

• $$y+2=7\left(x+1\right)$$  

• $$y+1=7\left(x+2\right)$$  

Multiple Choice

Write the slope-intercept form of the equation of the line through (1, 2) with slope 7.

Step 2: Rewrite the equation in slope-intercept form. (Simplify, then solve for y).

• $$y=7x-13$$  

• $$y=7x-5$$  

• $$y=7x+5$$  

• $$y=7x+13$$  

When given two points (x₁,y₁) and (x_2, y₂).

​Use point-slope form: y-y₁=m(x-x₁)

1. Use the slope-formula to calculate the slope.​

2. Plug in m and one of the points to write the equation.​

When given a point and a line parallel.

​Use point-slope form: y-y₁=m(x-x₁)

1. Parallel lines have the same slope. Identify the slope of your new line.

2. ​Use the slope and the point to write the equation of the line.​

When given a point and a line perpendicular.

​Use point-slope form: y-y₁=m(x-x₁)

1. Perpendicular lines have opposite reciprocal slopes. Identify the slope of your new line.

2. ​Use the slope and the point to write the equation of the line.​

Poll

How do you feel about writing equations of lines?

• I've got this.

• I'm getting there.

• I can do this with some help.

• I need help.