Answer:
The average rate of change is -3.
Step-by-step explanation:
Given : Function 
over the interval 2 ≤ x ≤ 4.
To find : What is the average rate of change ?
Solution :
Function over [2,4]
The rate of change is the slope of the line,
So, 
Substitute,
Therefore, The average rate of change is -3.
X = the number of months the tire was used
y = the thickness of the tire tread
y = -(3/7)x + 20
Substitute x for 20 (the number of months the tire was used) and solve for y.
The next question: Substitute x for 49 (the number of months the tire was used) and solve for y.
Answer:
21.142
Step-by-step explanation:
not sure it's correct
Answer: B) -8/9
Step-by-step explanation:
I would start by looking inside the parenthesis to see if anything could be simplified. We see the terms -5 and -3x, and upon realizing that there is no way to simplify, we can go ahead and just simplify the left side of the equation as much as we can before worrying about breaking the equation down. Distribute the -9 to the -5 and the -3x (multiply -9 by -5 and -9 by -3x). Multiplying two negative numbers will result in a positive value, so the left side of your equation should end up looking like this: 45+27x=21. Now, we can start working to get the variable on its own. Subtract 45 from both sides of the equation. On the left side this cancels out and leaves you with 27x. On the right side you have more of the negative value than positive value, so you end up with -24. The equation now looks like this: 27x=24. The only thing left to do is divide the equation by 27. On the left side of the equation, this leaves you with just x. On the right side, you get -24/27. Normally at this point I would divide out to get the decimal form (I prefer working with decimals) but bc the answer choices are all fractions there's not really a good use to, so instead let's just find the greatest common denominator (GCD) which would be 8. (Just as a clarification the GCD is the largest number you can divide both numbers by evenly.) Divide both the numerator and denominator by eight leaves you with -8/9. Therefore, x= -8/9.
