# limits and continuity problem

• Mar 16th 2013, 09:59 AM
ryu1
limits and continuity problem
1. given: Attachment 27555

need to find all the constants c for which the function is continuous in the section (-oo,+oo).

2.given: Attachment 27556 calculate the limit of Attachment 27557 (ignore the marks), from what i calculated it's supposed to be 17.2 but i think it's wrong somehow.
also need to prove that g(x) isn't continuous in the section (-oo,+oo)

I have tried for more than an hour to solve these and I am very frustrated by now.

appreciate your help, thanks.
• Mar 16th 2013, 11:00 AM
Plato
Re: limits and continuity problem
Quote:

Originally Posted by ryu1
1. given: Attachment 27555
need to find all the constants c for which the function is continuous in the section (-oo,+oo).
2.given: Attachment 27556 calculate the limit of Attachment 27557 .

For the first solve $|2+c|=1$.

For the second, just note that $\lim _{x \to \infty }}g(x) = - 4$
• Mar 16th 2013, 11:53 AM
ryu1
Re: limits and continuity problem
For the first I did solved that c must be -1 but I get confused that the instructions asks to "find ALL the possible c constants..." as if there's more than one?

For the second I did figured that out but it is right to place -4 in the limit problem later? like
g(x) = -4 so 10*(-4)^2 -3(-4) / 6 - (-4)

From that I got to 172/10. is that right?

Thanks a lot!
• Mar 16th 2013, 12:00 PM
Plato
Re: limits and continuity problem
Quote:

Originally Posted by ryu1
For the first I did solved that c must be -1 but I get confused that the instructions asks to "find ALL the possible c constants..." as if there's more than one?

For the second I did figured that out but it is right to place -4 in the limit problem later? like
g(x) = -4 so 10*(-4)^2 -3(-4) / 6 - (-4)

From that I got to 172/10. is that right?

Yes, the second is correct.

But for the first, $c=-1\text{ or }c=-3.$
• Mar 16th 2013, 12:07 PM
ryu1
Re: limits and continuity problem
Quote:

Originally Posted by Plato
Yes, the second is correct.

But for the first, $c=-1\text{ or }c=-3.$

Oh to solve the absolute value problem I need to:
One time calculate c assuming the expression inside the absolute value is positive (aka leaving it as it is).
And once more assuming it is negative (because the absolute value will negate the minus sign) which makes it -(2+c) = -2-c = 1 = c = -3 ?

How to prove that g(x) is not continuous in the section (-oo,+oo) ?
need to find g(x) = 6 so that I'd get a 0 in the denominator for that x?

Thanks a lot.
I have 6 problems I need to send out part of calculus course and I have been sitting on them for 4 hours making little progress (only answered about 3 ).