Answer:
slope: -3
equation: y = -3x
Step-by-step explanation:
the slope is "the amount of change in the y direction when you take one step to the right".
In the first graph you can see that (0,0) and (1,-3) are on the graph. So when you step from x=0 to x=1, the graph moves 3 units down. Hence the slope is -3. The minus sign means down.
Sometimes it is difficult to see the change in the y direction when only taking 1 step to the right. That's no problem, if you take e.g., 4 steps to the right, you have to divide the y change that you found by 4.
Written in a formula it is dy/dx, a.k.a: the y change divided by the x change.
So that takes care of the slope.
In a general formula for a line y = ax + b, the slope is the letter a.
b is used to move the graph up and down. The first graph moves through (0,0) so no b needed, hence the equation y = -3x.
If b would be, say, 5, the graph would be lifted up by 5. In fact, the point (0,b) will be the point where the graph crosses the y-axis. So you find b by finding the intersection with the y axis. x must be 0 at this point.
With this approach you can solve all assignments easily.
