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3 years ago

15

In a newspaper, it was reported that yearly robberies in Springfield were up 50% to 351 in 2013 from 2012. How many robberies we

re there in Springfield in 2012?

1 answer:

navik [9.2K]3 years ago

8 0

Answer:

Answer: There were 140 robberies in Springfield in 2012

Step-by-step explanation:

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Find the Fourier series of f on the given interval. f(x) = 1, ?7 < x < 0 1 + x, 0 ? x < 7

Zolol [24]

$f(x)=\begin{cases}1&\text{for }-7$

The Fourier series expansion of $f(x)$ is given by

$\dfrac{a_0}2+\displaystyle\sum_{n\ge1}a_n\cos\frac{n\pi x}7+\sum_{n\ge1}b_n\sin\frac{n\pi x}7$

where we have

$a_0=\displaystyle\frac17\int_{-7}^7f(x)\,\mathrm dx$
$a_0=\displaystyle\frac17\left(\int_{-7}^0\mathrm dx+\int_0^7(1+x)\,\mathrm dx\right)$
$a_0=\dfrac{7+\frac{63}2}7=\dfrac{11}2$

The coefficients of the cosine series are

$a_n=\displaystyle\frac17\int_{-7}^7f(x)\cos\dfrac{n\pi x}7\,\mathrm dx$
$a_n=\displaystyle\frac17\left(\int_{-7}^0\cos\frac{n\pi x}7\,\mathrm dx+\int_0^7(1+x)\cos\frac{n\pi x}7\,\mathrm dx\right)$
$a_n=\dfrac{9\sin n\pi}{n\pi}+\dfrac{7\cos n\pi-7}{n^2\pi^2}$
$a_n=\dfrac{7(-1)^n-7}{n^2\pi^2}$

When $n$ is even, the numerator vanishes, so we consider odd $n$ , i.e. $n=2k-1$ for $k\in\mathbb N$ , leaving us with

$a_n=a_{2k-1}=\dfrac{7(-1)-7}{(2k-1)^2\pi^2}=-\dfrac{14}{(2k-1)^2\pi^2}$

Meanwhile, the coefficients of the sine series are given by

$b_n=\displaystyle\frac17\int_{-7}^7f(x)\sin\dfrac{n\pi x}7\,\mathrm dx$
$b_n=\displaystyle\frac17\left(\int_{-7}^0\sin\dfrac{n\pi x}7\,\mathrm dx+\int_0^7(1+x)\sin\dfrac{n\pi x}7\,\mathrm dx\right)$
$b_n=-\dfrac{7\cos n\pi}{n\pi}+\dfrac{7\sin n\pi}{n^2\pi^2}$
$b_n=\dfrac{7(-1)^{n+1}}{n\pi}$

So the Fourier series expansion for $f(x)$ is

$f(x)\sim\dfrac{11}4-\dfrac{14}{\pi^2}\displaystyle\sum_{n\ge1}\frac1{(2n-1)^2}\cos\frac{(2n-1)\pi x}7+\frac7\pi\sum_{n\ge1}\frac{(-1)^{n+1}}n\sin\frac{n\pi x}7$

3 0

3 years ago

8. On Monday, 301 students went on a trip to the zoo. All 7 buses were filled and 7 students had to travel in

tankabanditka [31]

Answer:

42 Kids

Step-by-step explanation:

1st you have to subtract 7 form 301 so you get 294

2nd you divide 294 by 7 294/7

And you should get an answer of 42 Kids

5 0

3 years ago

Read 2 more answers

U need help ASAP!!!Please explain the answer

jolli1 [7]

ANSWER:
V= 3,619.1 km^3

EXPLANATION:
Simply plug in the radius (12 km) and height (24 km) into the cone volume formula.

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3 years ago

Which shows the best use of the associative and communitive properties to make simplifying 3/4 - 5 + 9 - 2/4 + 2 easier?

Alex Ar [27]

Answer:

The Answers A.

Step-by-step explanation:

3 0

3 years ago

Scientific notation of 0.000125

tester [92]

Answer:

1.25 × 10^-4

Step-by-step explanation:

Move the decimal until it's at 1.25. You had to go right 4 times so it's negative. If it were 12500 then you'd do it until it was 1.2500 which would be going left so it'd be a positive 4

5 0

3 years ago