Question

Can someone please explain functions and how find the y intercept when in this form

Answer 1

Slope-intercept form:  y = mx + b

[m is the slope, b is the y-intercept or the y value when x = 0 --> (0, y) or the point where the line crosses through the y-axis]

Since you know:

m = -2         Substitute/plug it into the equation

y = mx + b

y = -2x + b     To find b, plug in the point (7, -4) into the equation

-4 = -2(7) + b

-4 = -14 + b     Add 14 on both sides to get "b" by itself

-4 + 14 = -14 + 14 + b

10 = b       Now that you found b or the y-intercept, plug it in

y = -2x + 10

So to find the y-intercept, just plug in the point you were given into the equation once you had substituted in the slope. The slope tells you how many/the number of units from each point.

Slope can also be seen as:

$m=\frac{rise}{run}$

"rise" is the number of units you go up(+ number) or down(- number) from each point. (y-axis)

"run" is the number of units you go to the right from each point (x-axis)

For example, if you were to graph this line,

you could first plot a point at the y-intercept (0, 10). To plot the next point, you use the slope -2 or -2/1. So from (0, 10) you would go down 2 units and to the right 1 unit, therefore the next point you would plot would be (1, 8)