Finding the largest delta so that..

[PaulineS.]

Hi everybody,
I have been struggling with the following problem for a while now and the problem and I cannot even find the right solution after I went to my professors office hours.
So the problem is is the following:

let p(x)=-5+4x+4x^2
Find the largest delta so that absolute value of (p(x)-P(2.3)< 0.00033 when absolute value (x-2.3)<delta.

I have tried plugging in 2.3 for p and add 0.00033 to it and then equal it to p(x) and solve for x. I would then use the x closest to 2.3 and plug it in for the absolute value of (x-2.3) . But my answer is apparently wrong and I cannot seem to figure out why. I would really appreciate if someone could help me solve this!

 

[Dr.Peterson]

Please show your actual result, so we can see if you just made an arithmetic error or something. What you say sounds appropriate, almost. (I'm hoping that what you meant was that you both added and subtracted 0.00033, and took the nearest two of the four solutions.)

Also, when you say "my answer is apparently wrong ", how do you know? If a program is just telling you the answer is wrong, it could be you just used the wrong format; so please show exactly what the problem is telling you, including things like "to the nearest hundredth".

Did you ask your professor what was wrong with your answer, or just ask for general guidance?

 

[PaulineS.]

Please show your actual result, so we can see if you just made an arithmetic error or something. What you say sounds appropriate, almost. (I'm hoping that what you meant was that you both added and subtracted 0.00033, and took the nearest two of the four solutions.)

Also, when you say "my answer is apparently wrong ", how do you know? If a program is just telling you the answer is wrong, it could be you just used the wrong format; so please show exactly what the problem is telling you, including things like "to the nearest hundredth".

Did you ask your professor what was wrong with your answer, or just ask for general guidance?

Hi,

Thank you for your help! I found my error and could solve it now!
Thank you for your help though, much appreciated!

 

[Dr.Peterson]

That's the other reason we ask you to show your work ... people often find their own mistakes.