2. and 3. are already in slope intercept form.
1. y=4x-2
4. y=3x-2
Answer:

Step-by-step explanation:
Whenever you are adding exponents that have the same base (in this case the base is 9), you simply add the exponents. The base will stay the same because you are just adding the exponents

So, your answer is 
Hope this helps!
The circumference would be 16.328 mm.
Answer:
Step-by-step explanation:
I believe you have to make the -x to a positive by dividing because there is still an invisible one there, like:
-x/-1 < -6/-1
x > 6 . and switch the sign since you're dividing by a negative : )