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

Answer 1

Well, the first line has a slope of -3, and runs through 0, -1.

a line parallel to that one, will have the same exact slope of -3.

now, we know about this other parallel line that it runs through -3,1, and of course, since is parallel, it has a slope of -3

$\bf \begin{array}{ccccccccc} &&x_1&&y_1\\ &&(~ -3 &,& 1~) \end{array} \\\\\\ % slope = m slope = m\implies -3 \\\\\\ % point-slope intercept \stackrel{\textit{point-slope form}}{y- y_1= m(x- x_1)}\implies y-1=-3[x-(-3)] \\\\\\ y-1=-3(x+3) \implies y-1=-3x-9\implies y=-3x-8$