An equation of a line can be written in slope-intercept formy = mx + bwhere m is the slope and b is the y-intercept.

The y-intercept is where a line crosses the y-axis.

Suppose the slope of a line is 5 and the y-intercept is 2. How would this you write the equation of this line in slope-intercept form?

First write the slope-intercept form.y = mx + b

Now substitute 5 for m and 2 for b.y = 5x + 2

Where does the line cross the y-axis?◦ At the point (0, -4)◦ The y-intercept is -4.

What is the slope of the line?◦ The graph also crosses

the x-axis at (2, 0).◦ We can use the slope

formula to find our slope.

m = -4 – 0 = -4 = 2 0 – 2 -2

We know our slope is 2 and our y-intercept is -4, what is the equation of our line?

y = mx + by = 2x + (-4)y = 2x -4

Write the equation of a line with a slope of -2 and a y-intercept of 6.

y = mx + b y = -2x + 6

Write the equation of a line with a slope of -4/3 and a y-intercept of 1.

y = mx + b y = (-4/3) + 1

Where does the line cross the y-axis?◦ At the point (0, 2)◦ So the y-intercept b is 2.

The line also passes through the point (3, 0).

We can use these points to find the slope of the line. How? What formula do we use?◦ Using the slope formula,

we find that the slope m is -2/3.

◦ Write the equation of the line. y= mx + b y = (-2/3)x + 2

Step 1:First find the y-intercept. Substitute the

slope m and the coordinates of the given point (x, y) into the slope-intercept form, y = mx + b. Then solve for the y-intercept b.

Step 2:Then write the equation of the line.

Substitute the slope m and the y-intercept b into the slope-intercept form, y = mx + b.

Suppose we have a slope of -3 and it passes through the point (1, 2).◦ We first need to find the y-intercept. We

can do this by substituting our information into slope-intercept form and solving for b. y = mx + b 2 = -3(1) + b 2 = -3 + b Add 3 to both sides. 5 = b Now we know that the y-

intercept is 5. y = mx + b y = -3x + 5

Suppose we have a line with a slope of -1 and passes through the point (3, 4).

y = mx + b 4 = (-1)3 + b 4 = -3 + b 7 = b y = mx + b y = (-1)x + 7 y = -x + 7

Suppose we have a line with a slope of 2 and passes through the point (1, 3).

y = mx + b 3 = 2(1) + b 3 = 2 + b 1 = b y = mx + b y = 2x + 1

Write an equation f the line that passes through (-2,5) and (2,1).