What is i30 A. 1 B. -i C. -1 D. i

Find the sum or difference. a. -121 2 + 41 2 b. -0.35 - (-0.25)

s344n2d4d5 [400]

Answer:

2

Step-by-step explanation:

The reason an infinite sum like 1 + 1/2 + 1/4 + · · · can have a definite value is that one is really looking at the sequence of numbers

1

1 + 1/2 = 3/2

1 + 1/2 + 1/4 = 7/4

1 + 1/2 + 1/4 + 1/8 = 15/8

etc.,

and this sequence of numbers (1, 3/2, 7/4, 15/8, . . . ) is converging to a limit. It is this limit which we call the "value" of the infinite sum.

How do we find this value?

If we assume it exists and just want to find what it is, let's call it S. Now

S = 1 + 1/2 + 1/4 + 1/8 + · · ·

so, if we multiply it by 1/2, we get

(1/2) S = 1/2 + 1/4 + 1/8 + 1/16 + · · ·

Now, if we subtract the second equation from the first, the 1/2, 1/4, 1/8, etc. all cancel, and we get S - (1/2)S = 1 which means S/2 = 1 and so S = 2.

This same technique can be used to find the sum of any "geometric series", that it, a series where each term is some number r times the previous term. If the first term is a, then the series is

S = a + a r + a r^2 + a r^3 + · · ·

so, multiplying both sides by r,

r S = a r + a r^2 + a r^3 + a r^4 + · · ·

and, subtracting the second equation from the first, you get S - r S = a which you can solve to get S = a/(1-r). Your example was the case a = 1, r = 1/2.

In using this technique, we have assumed that the infinite sum exists, then found the value. But we can also use it to tell whether the sum exists or not: if you look at the finite sum

S = a + a r + a r^2 + a r^3 + · · · + a r^n

then multiply by r to get

rS = a r + a r^2 + a r^3 + a r^4 + · · · + a r^(n+1)

and subtract the second from the first, the terms a r, a r^2, . . . , a r^n all cancel and you are left with S - r S = a - a r^(n+1), so

(IMAGE)

As long as |r| < 1, the term r^(n+1) will go to zero as n goes to infinity, so the finite sum S will approach a / (1-r) as n goes to infinity. Thus the value of the infinite sum is a / (1-r), and this also proves that the infinite sum exists, as long as |r| < 1.

In your example, the finite sums were

1 = 2 - 1/1

3/2 = 2 - 1/2

7/4 = 2 - 1/4

15/8 = 2 - 1/8

and so on; the nth finite sum is 2 - 1/2^n. This converges to 2 as n goes to infinity, so 2 is the value of the infinite sum.

8 0

3 years ago

Help me on this question

tatyana61 [14]

Answer:

The single transformation that maps shape A into shape B is 4 steps right and 3 steps down.

8 0

3 years ago

A new Firestone tire is guaranteed to last for 40,000 miles. The actual mean life of the tires is 47,000 miles with a standard d

Rus_ich [418]

Answer:

a) 95.99%

b) 4.01%

c) 00.62%

Step-by-step explanation:

Explanation is given in the attachments.

3 0

2 years ago

The sum of 4 consecutive even integers is -12. find the largest integer.

Ipatiy [6.2K]

Answer:

The largest even integer is 0

Step-by-step explanation:

Given as :

The sum of four consecutive even number = - 12

Let The first even number = 2 x

The second even number = (2 x + 2)

The third even number = (2 x + 4)

The fourth even number = (2 x + 6)

According to question

sum of four consecutive even number = - 12

Or, 2 x + (2 x + 2) + (2 x + 4) + (2 x + 6) = - 12

Or, (2 x + 2 x + 2 x + 2 x) + (2 + 4 + 6) = - 12

Or, 8 x + 12 = - 12

Or, 8 x = - 12 - 12

Or, 8 x = - 24

∴ x = $\frac{- 24}{8}$

i.e x = - 3

now, putting the value of x

The first even number = 2 × - 3 = - 6

The second even number = (2 × - 3 + 2) = - 6 + 2 = - 4

The third even number = (2 × - 3 + 4) = - 6 + 4 = - 2

The fourth even number = (2 × - 3 + 6) = - 6 + 6 = 0

So, The largest even integer = 0

Hence, The largest even integer is 0 Answer

6 0

3 years ago

If rain is falling at 0.5 inches per hour and 1.5 inches have already accumulated, how many hours must have passed if there are

zavuch27 [327]

Given :

Rain is falling at 0.5 inches per hour and 1.5 inches have already accumulated.

To Find :

How many hours must have passed if there are 5 inches of rain .

Solution :

Let , after x hours rain accumulated is 5 inches .

We know , general equation of line :

y = mx +c

Here , m = 0.5 and c = 1 .

So , equation of rain accumulated is :

$y=0.5x+1$

Now , putting value of x = 5 hours .

We get :

$y=0.5\times 5+1\\\\y=2.5+1=3.5\ inches$

Hence , this is the required solution .

7 0

3 years ago