The slope is 4 & the line passes thru (1,-8), what equation should he use to find the y intercept

Find the Equation of a Line Given That You Know Its Slope and Y-Intercept. The equation of a line is typically written as y=mx+b where m is the slope and b is the y-intercept. If you know the slope (m) any y-intercept (b) of a line, this page will show you how to find the equation of the line.

the direct variation says that:

then the equation is of the form is given by:

            where k is the constant variation.

from the given table:

consider any value of x and m(x)=y

x = 2 and m(x)=y = 3

substitute these value in [1]; we have;

divide both sides by 2 we get;

⇒

check:

put x = -1 and m(x) = -1.5

substitute in the equation:

-1.5 = -1.5                   true

therefore, the function m(x) represents a direct variation

graph of this function as shown below: