The graphs of the equations y=3x+13 and y-kx=15 are parallel when k equals..?

Question

The graphs of the equations y=3x+13 and y-kx=15 are parallel when k equals..?

Answer 1

Since parallel lines have exactly the same slope m, the coefficient of x

y = 3x + 13

has slope m = 3,

And

y - kx = 15

In slope intercept form is

y = kx + 15

In order for the lines to be parallel, k must equal m.

Give it a try.