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3 years ago

10x-7-4x=41 Please solve for x and show your work

Mathematics

1 answer:

sergey [27]3 years ago

6 0

I never learned this yet...

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Find two linearly independent solutions to the equation y"-2xy'+2y=0 in the form of a power series.

ioda

We want a solution in the form

$y=\displaystyle\sum_{n\ge0}a_nx^n$

with derivatives

$y'=\displaystyle\sum_{n\ge0}(n+1)a_{n+1}x^n$

$y''=\displaystyle\sum_{n\ge0}(n+2)(n+1)a_{n+2}x^n$

Substituting $y$ and its derivatives into the ODE,

$y''-2xy'+2y=0$

gives

$\displaystyle\sum_{n\ge0}(n+2)(n+1)a_{n+2}x^n-2\sum_{n\ge0}(n+1)a_{n+1}x^{n+1}+2\sum_{n\ge0}a_nx^n=0$

Shift the index on the second sum to have it start at $n=1$ :

$\displaystyle\sum_{n\ge0}(n+1)a_{n+1}x^{n+1}=\sum_{n\ge1}na_nx^n$

and take the first term out of the other two sums. Then we can consolidate the sums into one that starts at $n=1$ :

$\displaystyle(2a_2+2a_0)+\sum_{n\ge1}\bigg[(n+2)(n+1)a_{n+2}+(2-2n)a_n\bigg]x^n=0$

and so the coefficients in the series solution are given by the recurrence,

$\begin{cases}a_0=y(0)\\a_1=y'(0)\\(n+2)(n+1)a_{n+2}=2(n-1)a_n&\text{for }n\ge0\end{cases}$

or more simply, for $n\ge2$ ,

$a_n=\dfrac{2(n-3)}{n(n-1)}a_{n-2}$

Note the dependency between every other coefficient. Consider the two cases,

If $n=2k$ , where $k\ge0$ is an integer, then

$k=0\implies n=0\implies a_0=a_0$

$k=1\implies n=2\implies a_2=-a_0=2^1\dfrac{(-1)}{2!}a_0$

$k=2\implies n=4\implies a_4=\dfrac{2\cdot1}{4\cdot3}a_2=2^2\dfrac{1\cdot(-1)}{4!}a_0$

$k=3\implies n=6\implies a_6=\dfrac{2\cdot3}{6\cdot5}a_4=2^3\dfrac{3\cdot1\cdot(-1)}{6!}a_0$

$k=4\implies n=8\implies a_8=\dfrac{2\cdot5}{8\cdot7}a_6=2^4\dfrac{5\cdot3\cdot1\cdot(-1)}{8!}a_0$

and so on, with the general pattern

$a_{2k}=\dfrac{2^ka_0}{(2k)!}\displaystyle\prod_{i=1}^k(2i-3)$

If $n=2k+1$ , then

$k=0\implies n=1\implies a_1=a_1$

$k=1\implies n=3\implies a_3=\dfrac{2\cdot0}{3\cdot2}a_1=0$

and we would see that $a_{2k+1}=0$ for all $k\ge1$ .

So we have

$y(x)=\displaystyle\sum_{k\ge0}\bigg[a_{2k}x^{2k}+a_{2k+1}x^{2k+1}\bigg]$

so that one solution is

$\boxed{y_1(x)=\displaystyle a_0\sum_{k\ge0}\frac{2^k\prod\limits_{i=1}^k(2i-3)}{(2k)!}x^{2k}}$

and the other is

$\boxed{y_2(x)=a_1x}$

I've attached a plot of the exact and series solutions below with $a_0=y(0)=1$ , $a_1=y'(0)=1$ , and $0\le k\le5$ to demonstrate that the series solution converges to the exact one.

6 0

3 years ago

Can someone help me with this question

mr Goodwill [35]

Answer:

53.3

Step-by-step explanation:

34^2=1156

41^2=1681

1156+1681=2837

Square root of 2837 is 53.26 which rounded to the nearest tenth is 53.3

7 0

3 years ago

A softball pitcher has a 0.507 probability of throwing a strike for each pitch. If the softball pitcher throws 15 pitches, what

Elena L [17]

Answer:

The probability that the pitcher throws exactly 8 strikes out of 15 pitches is approximately 0.199

Step-by-step explanation:

The given probability that the pitcher throws a strike, p = 0.507

The number of pitches thrown by the pitcher = 15 pitches

The probability that the pitcher does not throw a strike, q = 1 - P

∴ q = 1 - 0.507 = 0.493

By binomial theorem, we have;

$P(X = r) = \dbinom{n}{r}p^{r} \cdot q^{n-r}= \dbinom{n}{r}p^{r} \cdot \left (1-p \right )^{n-r}$

When X = r = 8, and n = 15, we get;

The probability that the pitcher throws exactly 8 strikes out of 15 pitches, P(8), is given as follows

P(8) = ₁₅C₈ × 0.507⁸ × (1 - 0.507)⁽¹⁵ ⁻ ⁸⁾ = 6,435 × 0.507⁸ × 0.493⁷ ≈ 0.199

8 0

3 years ago

Find the missing measure of each right triangle. Round to the nearest tenth if necessary.

Irina18 [472]

A squared + b squared = c squared
8.6^2+14.7^2=c^2
73.96+216.09=c^2
square root both sides and...
c=17.03085
Your answer is A
Hope this helps

3 0

4 years ago

Given that EF is a diameter of circle D, which of the following arcs must be a major arc?

Rainbow [258]

Answer:

Arc ECG is the major arc

Step-by-step explanation:

Arc ECG is made by an angle which is greater than 180°.

All the other arcs listed are made by angles which are 180° or less than.

The greater the angle measure the greater the arc length.

8 0

3 years ago