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.

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.

imstuck · Answer

Do you know how to tell if 2 lines are parallel to each other?

anonymous · Answer

Not really

imstuck · Answer

They have the same slope.  The slope of the first line is given to you as -3.  That means that the second line you find an equation to will also have a slope of -3.

imstuck · Answer

Do you know how to use the point-slope formula?

anonymous · Answer

Yah it's y-y1=m(x-x1)

imstuck · Answer

Good!  That's half the battle!  It's easy from here on out!

imstuck · Answer

Use the slope they gave you (-3) in place of the "m" in your point-slope equation and then use the point they gave you (-3, 1) and replace the y1 with the 1 and the x1 with the -3.  Like so:

imstuck · Answer

$$y-1=-3(x-(-3))$$or$$y-1=-3(x+3)$$

imstuck · Answer

Now "do the math".  Distribute the -3 into the parenthesis and you get$$y-1=-3x-9$$

imstuck · Answer

Add the 1 to both sides to isolate the y:$$y=-3x-9+1$$which of course is the same thing as$$y=-3x-8$$And that is your new equation with the slope of -3 that goes through the point (-3, 1)

imstuck · Answer

It's A in your choices.

anonymous · Answer

Ok thank you so much

imstuck · Answer

You're very welcome!  Just do all of those types the same way...they all "work" the same!