A line has a slope of –3 and a y-intercept of (0, –1). What is the equation of the line that is parallel to the given line and passes through the point (–3, 1)?
A.y = –3x – 8
B.y = 3x + 10
C.y = –3x + 4
D.y = 1/3x+2

Question

A line has a slope of –3 and a y-intercept of (0, –1). What is the equation of the line that is parallel to the given line and passes through the point (–3, 1)?
A.y = –3x – 8 
B.y = 3x + 10 
C.y = –3x + 4 
D.y = 1/3x+2

mathstudent55 · Answer

Start with the point-slope form of the equation of a line

y = mx + b

anonymous · Answer

Line is parallel...therefore slope is same hence answer has to be from A or C!
Check the equation which satisfies the point (-3,1) I guess it's A

mathstudent55 · Answer

You are told that the given line has a slope of -3, and you are looking for a parallel line.
Parallel lines have equal slopes. That means your line has a slope of -3 too.

mathstudent55 · Answer

Now you can put the slope in the equation:

y = mx + b
y = -3x + b

Now to see which equation is correct, replace x and y in the equation above by the coordinates of the given point (-3, 1).

1 = -3(-3) + b
1 = 9 + b
-8 = b
b = -8

Since you now know b, you can finally write the complete equation of the new line:

y = -3x - 8

anonymous · Answer

thanks for the help :)

mathstudent55 · Answer

You're welcome.