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Dec 1 2013 09:49pm
got a few problems im struggling with, any help is greatly appreciated

#1 the function is defined by f(x)= radical(25-x^2) for -5<x<5

now: let g be the function defined by g(x)= {f(x) for -5<x<-3
and {x+7 for -3<x<5

is g continuous at x=-3? use definition of continuity to explain answer



im so confused.
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Dec 1 2013 10:06pm
for a function to be continuous, you must have:
1.) the left hand and right hand limits must exist and be the same value
2.) the function value must equal the limit value

If you evaluate the limit for both of your piece-wise functions, you see a limit exists and is the same value for both (limit=4)
However, your domain of g(x) does not include -3, so f(-3) does NOT equal the limit value.
So g(x) is NOT continuous.
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Dec 1 2013 10:20pm
thank you, i think that cleared some things up. what makes you so sure the domain of g(x) doesnt include -3?
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Dec 1 2013 10:24pm
Quote (known954 @ Dec 1 2013 11:20pm)
thank you, i think that cleared some things up. what makes you so sure the domain of g(x) doesnt include -3?


you have the domain listed.
-5<x<-3
and
-3<x<5

If you combine both of your domains, you have:
(-5,-3) union (-3,5)

So clearly, -3 is not in your domain
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Dec 1 2013 10:29pm
sorry its actually -5<x<-3
and -3<x<5

does that change the answer?
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Dec 1 2013 10:34pm
Quote (known954 @ Dec 1 2013 11:29pm)
sorry its actually -5<x<-3
and -3<x<5

does that change the answer?


yes.
Since g(-3) exists, it equals 4
So the limit at -3 equals g(-3). This means the function is continuous
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Dec 1 2013 10:40pm
got it :)

now area of square is A=s^2

if area is 4 square inches and its side length is increasing at a rate of .5 inch per second, at what rate is the area changing? with respect to time (t seconds)
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Dec 1 2013 10:59pm
Quote (known954 @ Dec 1 2013 10:40pm)
got it :)

now area of square is A=s^2

if area is 4 square inches and its side length is increasing at a rate of .5 inch per second, at what rate is the area changing? with respect to time (t seconds)


probably one of the main concept of calculus is the derivative
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Dec 2 2013 12:01am
guys, why do you use the 'radical' when you actually mean 'square root'?
in mathematics a radical has a very clear definition in those areas the term is used but square root is not one of them
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