Hello Carter:
This one is super easy. You should take a look in your book at the example problems on this, because this is a formula that you will need to learn.
The equation of a line can be represented by the formula y = mx + b, where the following are true:
a) x is the x coordinate
b) y is the y coordinate
c) m is the slope (represented as the change in y over the change in x)
d) b is the y intercept (the place where the line crosses the y axis.
So in this problem, you just substitute the values in for m and b, because:
What is the equation of a line that has a slope of 3 and a y-intercept of -3?
The problem TELLS you these numbers.
a y-intercept of -3 becomes the value for the b in the equation: so you write
y = mx +b and substitute -3 in for b which means you are ADDING a negative, so now it's a negative and it looks like this: y = mx -3
and then m is the slope--the problem tells you that the line has a slope of 3
so you substitute 3 in for m (You could also use 3/1 because 3 divided by 1 is still 3)
so now your equation looks like this:
y = 3x -3
AND YOU ARE DONE!
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