**Write an equation of a line given its slope and ***y***-intercept**

** **

we found the slope of a line from the equation of the line by solving the equation for *y*. For example, we found that the slope of the line with equation

*y = 4x + 8*

is 4, the coefficient of *x*. What does the number **8 **represent?

To find out, suppose a line has slope *m *and *y*-intercept (0, *b*). We can find an equation of this line by choosing another point (*x*, *y*) on the line, as shown in Figure . Using the slope formula,

m =

m =

mx = y – b Milyiply byx.

mx + b = y Add b.

y = mx + b.

This last equation is called the *slope-intercept form *of the equation of a line, because we can identify the slope *m *and *y*-intercept (0, *b*) at a glance.