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Tom [10]
3 years ago
10

B) What is the 4 times of the sum of 3and9? ​

Mathematics
2 answers:
Sliva [168]3 years ago
7 0
I’m confuse about the question I don’t know you mean in equation but 4(x+3)= 9
Mashcka [7]3 years ago
3 0

Answer:

108

Step-by-step explanation:

sum is a fancy word for add so 3+9=27 and 27*4=108

You might be interested in
Xy''+2y'-xy by frobenius method
aalyn [17]
First note that x=0 is a regular singular point; in particular x=0 is a pole of order 1 for \dfrac2x.

We seek a solution of the form

y=\displaystyle\sum_{n\ge0}a_nx^{n+r}

where r is to be determined. Differentiating, we have

y'=\displaystyle\sum_{n\ge0}(n+r)a_nx^{n+r-1}
y''=\displaystyle\sum_{n\ge0}(n+r)(n+r-1)a_nx^{n+r-2}

and substituting into the ODE gives

\displaystyle x\sum_{n\ge0}(n+r)(n+r-1)a_nx^{n+r-2}+2\sum_{n\ge0}(n+r)a_nx^{n+r-1}-x\sum_{n\ge0}a_nx^{n+r}=0
\displaystyle \sum_{n\ge0}(n+r)(n+r-1)a_nx^{n+r-1}+2\sum_{n\ge0}(n+r)a_nx^{n+r-1}-\sum_{n\ge0}a_nx^{n+r+1}=0
\displaystyle \sum_{n\ge0}(n+r)(n+r+1)a_nx^{n+r-1}-\sum_{n\ge0}a_nx^{n+r+1}=0
\displaystyle r(r+1)a_0x^{r-1}+(r+1)(r+2)a_1x^r+\sum_{n\ge2}(n+r)(n+r+1)a_nx^{n+r-1}-\sum_{n\ge0}a_nx^{n+r+1}=0
\displaystyle r(r+1)a_0x^{r-1}+(r+1)(r+2)a_1x^r+\sum_{n\ge2}(n+r)(n+r+1)a_nx^{n+r-1}-\sum_{n\ge2}a_{n-2}x^{n+r-1}=0
\displaystyle r(r+1)a_0x^{r-1}+(r+1)(r+2)a_1x^r+\sum_{n\ge2}\bigg((n+r)(n+r+1)a_n-a_{n-2}\bigg)x^{n+r-1}=0

The indicial polynomial, r(r+1), has roots at r=0 and r=-1. Because these roots are separated by an integer, we have to be a bit more careful, but we'll get back to this later.

When r=0, we have the recurrence

a_n=\dfrac{a_{n-2}}{(n+1)(n)}

valid for n\ge2. When n=2k, with k\in\{0,1,2,3,\ldots\}, we find

a_0=a_0
a_2=\dfrac{a_0}{3\cdot2}=\dfrac{a_0}{3!}
a_4=\dfrac{a_2}{5\cdot4}=\dfrac{a_0}{5!}
a_6=\dfrac{a_4}{7\cdot6}=\dfrac{a_0}{7!}

and so on, with a general pattern of

a_{n=2k}=\dfrac{a_0}{(2k+1)!}

Similarly, when n=2k+1 for k\in\{0,1,2,3,\ldots\}, we find

a_1=a_1
a_3=\dfrac{a_1}{4\cdot3}=\dfrac{2a_1}{4!}
a_5=\dfrac{a_3}{6\cdot5}=\dfrac{2a_1}{6!}
a_7=\dfrac{a_5}{8\cdot7}=\dfrac{2a_1}{8!}

and so on, with the general pattern

a_{n=2k+1}=\dfrac{2a_1}{(2k+2)!}

So the first indicial root admits the solution

y=\displaystyle a_0\sum_{k\ge0}\frac{x^{2k}}{(2k+1)!}+a_1\sum_{k\ge0}\frac{x^{2k+1}}{(2k+2)!}
y=\displaystyle \frac{a_0}x\sum_{k\ge0}\frac{x^{2k+1}}{(2k+1)!}+\frac{a_1}x\sum_{k\ge0}\frac{x^{2k+2}}{(2k+2)!}
y=\displaystyle \frac{a_0}x\sum_{k\ge0}\frac{x^{2k+1}}{(2k+1)!}+\frac{a_1}x\sum_{k\ge0}\frac{x^{2k+2}}{(2k+2)!}

which you can recognize as the power series for \dfrac{\sinh x}x and \dfrac{\cosh x}x.

To be more precise, the second series actually converges to \dfrac{\cosh x-1}x, which doesn't satisfy the ODE. However, remember that the indicial equation had two roots that differed by a constant. When r=-1, we may seek a second solution of the form

y=cy_1\ln x+x^{-1}\displaystyle\sum_{n\ge0}b_nx^n

where y_1=\dfrac{\sinh x+\cosh x-1}x. Substituting this into the ODE, you'll find that c=0, and so we're left with

y=x^{-1}\displaystyle\sum_{n\ge0}b_nx^n
y=\dfrac{b_0}x+b_1+b_2x+b_3x^2+\cdots

Expanding y_1, you'll see that all the terms x^n with n\ge0 in the expansion of this new solutions are already accounted for, so this new solution really only adds one fundamental solution of the form y_2=\dfrac1x. Adding this to y_1, we end up with just \dfrac{\sinh x+\cosh x}x.

This means the general solution for the ODE is

y=C_1\dfrac{\sinh x}x+C_2\dfrac{\cosh x}x
3 0
3 years ago
on 5 day of every week ,Jackie run 2 1/2 mile in the morning.How many total mile doe Jackie run every week
telo118 [61]

Answer:12 1/2

Step-by-step explanation:

6 0
1 year ago
PLEASE ANSWER!!! Brainliest to whoever answers at first!Order the following expressions by their values from least to greatest.
Brilliant_brown [7]

Answer:

  -j, 0, j-k

Step-by-step explanation:

j is a positive number, so -j will be less than 0.

j is a number greater than k, so j - k will be greater than 0.

From least to greatest, the order is ...

  -j, 0, j-k

5 0
4 years ago
The circle below is center Ed at O. Decide which length,if any, is definitely the same as the length. a) AD. b) BC. Justify your
Mars2501 [29]

Answer:

Point O is the center of the circle.

<u>Part (a)</u>

\overline{A\:\!F} is a chord.

\overline{OD} is a segment of the radius and is perpendicular to  \overline{A\:\!F}

If a radius is perpendicular to a chord, it bisects the chord (divides the chord into two equal parts).

Therefore, \overline{AD}=\overline{DF}

<u>Part (b)</u>

If \overline{BE} was extended past point E to touch the circumference it would be a chord.

As \overline{OC} is perpendicular to \overline{BE},  it would bisect the chord, but as \overline{BE} is only a portion of a chord, \overline{OC} <u>does not</u> bisect \overline{BE}.

Therefore, there is no length equal to \overline{BC}.

5 0
2 years ago
Please dont answer with anything bad :((( extremely need help
svetoff [14.1K]

Answer:

120°

Step-by-step explanation:

A line must add up to 180°.

The sum of angles in a triangle also adds up to 180°.

Step 1: Find measures interior angles.

3x = 180

x = 60°

Step 2: Find measures of exterior angels.

x + 60 = 180

x = 120°

5 0
3 years ago
Read 2 more answers
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