Answer:
y = 3x - 3
Step-by-step explanation:
This more of a guess than a reality of method. You have to try and guess which number when multiplied by 4 will give 9. It won't happen directly.
The best clue is provide by (0,-3).
So let's start with a general linear equation.
y = mx + b
If you put in 0 for x then mx disappears and you are are left with y = - 3
That means that b = - 3
So now you have
y = mx - 3
Now try another one
y = mx - 3
y = 9
x = 4
9 = mx - 3
9 = 4m - 3 Add 3 to both sides
9+3 = 4m-3+3 Combine
12 = 4m Divide by 4
12/4 = 4m/4
3 = m
So the equation you want so far, is y = 3x - 3 Does it work for anything else?
Try - 3 , - 12 . If it works for this, it should work for anything.
y = 3*-3 - 3
y = -9 -3
y = - 12
and it does work, so that's your answer.
