Intermediate Value Theorem
Key Questions
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To answer this question, we need to know what the intermediate value theorem says.
The theorem basically sates that:
For a given continuous functionf(x)f(x) in a given interval[a,b][a,b] , for someyy betweenf(a)f(a) andf(b)f(b) , there is a valuecc in the interval to whichf(c) = yf(c)=y .It's application to determining whether there is a solution in an interval is to test it's upper and lower bound.
Let's say that our
f(x)f(x) is such thatf(x) = x^2 - 6*x + 8f(x)=x2−6⋅x+8 and we want to know if there is a solution between11 and33 (in the[1,3][1,3] interval).
f(1) = 3f(1)=3
f(3) = -1f(3)=−1
From the theorem (since all polynomials are continuous), we know that there is acc in[1,3][1,3] such thatf(c) = 0f(c)=0 (-1 <= 0 <= 3−1≤0≤3 )//Hope it helps.
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Answer:
There are several definitions of continuous function, so I give you several...
Explanation:
Very roughly speaking, a continuous function is one whose graph can be drawn without lifting your pen from the paper. It has no discontinuities (jumps).
Much more formally:
If
A sube RR thenf(x):A->RR is continuous iffAA x in A, delta in RR, delta > 0, EE epsilon in RR, epsilon > 0 : AA x_1 in (x - epsilon, x + epsilon) nn A, f(x_1) in (f(x) - delta, f(x) + delta) That's rather a mouthful, but basically means that
f(x) does not suddenly jump in value.Here's another definition:
If
A andB are any sets with a definition of open subsets, thenf:A->B is continuous iff the pre-image of any open subset ofB is an open subset ofA .That is if
B_1 sube B is an open subset ofB andA_1 = { a in A : f(a) in B_1 } , thenA_1 is an open subset ofA . -
Answer:
It means that a if a continuous function (on an interval
A ) takes 2 distincts valuesf(a) andf(b) (a,b in A of course), then it will take all the values betweenf(a) andf(b) .Explanation:
In order to remember or understand it better, please know that the math vocabulary uses a lot of images. For instance, you can perfectly imagine an increasing function! It's the same here, with intermediate you can imagine something between 2 other things if you know what I mean. Don't hesitate to ask any questions if it's not clear!