Solving Problems: Rates of Change and Value Adjustments in Math

[GLprincess02]

There are two more problems I am unsure of, so if someone could just check my answers, I'd be grateful.

Problem:
Suppose y=4/x.
a) Find the rate of change from x=1 to x=2
b) Find the rate of change from x=2 to x=3
c) Why are a and b not equal?

Answers:
a) -2
b) -2/3
c) It is a hyperbola

Problem:
Suppose s=16d^2
a) How does the value of s change if d is doubled?
b) How does the value of s change if d is divided by 3?

Answers:
a) s is multiplied by 2
b) s is divided by 3

 

[courtrigrad]

Problem 1 is correct
Problem 2 is incorrect. just look at d = 1. Since it is a squared term it would be multiplied by 4. And if it is divided by 3 S is (1/3)^2 = 1/9 S.

 

[GLprincess02]

Oh ok, I disregarded the square part. And you would still divide by 1/9 in part b, right? So the answer would be "s is divided by 1/9?"

 

[courtrigrad]

For your answer in (b) it would be divided by 9. Again this is because we have a squared term. If s = 16d then it would be divided by 3 because of the linear term. And s would also be multiplied by 2 if we had the linear term.

 

[courtrigrad]

no S would be divided by 9

 

[GLprincess02]

Sorry, I hadn't read your second post before I edited mine.
And I get it it now. Thank you for your help!

 

[GLprincess02]

Cool! But I'm confused...how do you know I like it?

 

[GLprincess02]

Lol ok that makes sense! I use pretty much the same username for every site I'm on. Is courtigrad your name on youtube, too?