# Writing-Equations-of-Lines ```Last week we learned 3 ways of graphing a line.
The first was____________________form, which looks like 𝑦 = 𝑚𝑥 + 𝑏 and it
needs a __________ and a _____________ in order to plot the graph of the line.
The second method used a special formula, similar to the slope of a line
equation, called ___________________________. This formula needed a __________ and a
____________ in order to work its way into slope-intercept form which we can
graph.
The last method we learned gave us the situation where we are given
two points and we needed to find the graph of the line that would pass
through both points. With this method you first needed to calculate the
__________. Then with the __________ and__________________________ you take this
information at use either formula in the previous two methods to find the full
equation of this line.
Reminder from L-8 (Classifying Slopes of Lines)
 To decide if lines are parallel or perpendicular, it would be good to first
write the lines in ___________________________ form, which is 𝑦 = 𝑚𝑥 + 𝑏.
 Parallel lines have slopes that are ____________________________.
 Perpendicular lines have slopes that are ________________________________.
 Otherwise the lines just _____________________________.
1. Decide if the lines are perpendicular: y 
1
x  10 and y  3x . YES or NO
3
5
x  2?
7
7
C) y   x  3
5
2. Which of the following lines is parallel to y  
A) y 
5
x  5
7
3. A line parallel to y 
2
A) y   x  7
3
B) y 
5
x6
7
2
x  7 is _______________.
3
3
3
B) y  x  2
C) y   x  7
2
2
D) y 
5
x9
7
D) y 
2
x 1
3
4. Which is the slope of a line perpendicular to the line 7 x  y  9 ?
1
1
A) -7
B)
C) 7
D) 
7
7
1
5. The line y   x  3 is perpendicular to which line?
2
1
1
A) y   x  6
B) y  2x  3
C) y  x  1
2
2
D) y  2x
1
x  6 and y  5x  6 . The lines represented
5
by these equations are perpendicular. Which statement explains why this is true?
6. Consider the two equations: y 
A) The constants in the two equations are the same.
B) Both equations are written in slope-intercept form.
C) The coefficients of y are the same because they have the same slope in each.
D) The coefficients of x in the 2 equations are reciprocals and have opposite signs.
7. What best describes the relationship between the lines with equations y  2x  4
1
and y  2x  ?
4
A) perpendicular
B) parallel C) same line D) neither parallel nor perpendicular
Think of the equation 𝑦 = 2𝑥 − 3...
What is the slope?_____
What is the slope of a line parallel to 𝑦 = 2𝑥 − 3?_________
ex 1: So...Write an equation of the line passing through the point (-1,1) that is
parallel to the line with the equation y = 2x – 3.
Before that...What information do we have in this question? What's given to you?
Think of the equation 𝑦 = −2𝑥 + 2...
What is the slope?_____
What is the slope of a line perpendicular to 𝑦 = −2𝑥 + 2?_________
ex 2: So... Write an equation of the line j passing through the point (2,3) that is
perpendicular to the line k with the equation y = -2x + 2.
Before that...What information do we have in this question? What's given to you?
```