Mathematical Induction

Содержание

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Mathematical Induction Let Sn, n = 1,2,3,… be statements involving positive

Mathematical Induction

Let Sn, n = 1,2,3,… be statements involving positive integer

numbers n.
Suppose that
1. S1 is true.
2. If Sk is true, then Sk +1 is also true.

Then Sn is true for all positive integer numbers n.

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for all positive integers n. If it is assumed that the

for all positive integers n. If it is assumed that the

sequence {xn} converges, then

Question 1. Let x1 = 1 and

Solution. First, we find fixed points of the relationship

That is, we find solutions of the equation

Next, we calculate a few terms of the sequence.

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Therefore, the principle of mathematical induction tells us that for any

Therefore, the principle of mathematical induction tells us that for any

positive integer n.

Our first statement S1:

The general statement Sn:

The first statement S1 is correct.
Let us assume that a statement Sk : is also correct. Then

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in both parts of the relationship But, what if this is

in both parts of the relationship

But, what if this is a

free-response question?
Then we can pass to the limit

Since we know that the sequence xn converges

Since is a continuous function for we obtain

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Question 1: Answers to Questions from Light #2: Sequences and Limits

Question 1:

Answers to Questions from Light #2:
Sequences and Limits

Question 2:

Question

4:

Question 3a:

Question 3b:

Integer part of

Question 5:

You have to show that

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Calculus++ Also known as Hysterical Calculus

Calculus++

Also known as Hysterical Calculus

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Question 1b. Find the limit of the sequence Solution. We have Using the equivalence we obtain

Question 1b. Find the limit of the sequence

Solution. We have

Using the

equivalence

we obtain

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Using now the equivalence we obtain Therefore,

Using now the equivalence

we obtain

Therefore,

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Question 2b. Find the following limit Solution. Actually, the equivalence gives

Question 2b. Find the following limit

Solution. Actually, the equivalence

gives an incorrect

result for this limit.

To obtain a correct result we have to use

Incorrect!

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The last equivalence yields

The last equivalence yields

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Question 3. Find the following limit Solution. We have to find

Question 3. Find the following limit

Solution. We have to find precise

equivalent functions for each term at x = 0

Therefore,

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A similar (but even more difficult) calculation yields Therefore and

A similar (but even more difficult) calculation yields

Therefore

and

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Picture of the Week

Picture of the Week

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Question 8. The initial location of a snail is the point

Question 8. The initial location of a snail is the point

S1 = (0,0).
The first 3 turning points, keeping the snail confined inside a unit square, are given by S2 = (½, 1), S3 = (1, ½), and S4 = (½, 0).
After that the snail always heads towards the midpoint of the next path segment that it sees, without crossing its own path.
That is, the coordinates (xn, yn) of the turning points Sn are given by

and

for n = 5,6,7,…

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a) Show that xn+3 + xn+2 + xn+1 + ½ xn

a) Show that xn+3 + xn+2 + xn+1 + ½ xn

= 2,
and find a similar relationship for the y-coordinates.
b) Find the x and y coordinates of the limiting point of the snail path.
c) Repeat parts a) and b) for a snail confined inside an isosceles triangle.
The initial location of the snail is S1 = (0,0).
The first 2 turning points are S2 = (¾, ½) and S3 = (½, 0).
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Snail path in the xy – plane. y

Snail path in the xy – plane.

y

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Solution. Write down the characteristic equation for the formula Unfortunately, this

Solution. Write down the characteristic equation for the formula

Unfortunately, this

equation has only two real solutions, but it definitely has a solution

Divide the characteristic polynomial by

Denote

then

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Therefore Thus If the sequence xn converges to , then Passing

Therefore

Thus

If the sequence xn converges to , then

Passing to

the limit in the relationship

we obtain

Hence

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Snail path in the xy – plane. y

Snail path in the xy – plane.

y