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2 years ago

5cm

Mathematics

1 answer:

Maksim231197 [3]2 years ago

5 0

Answer:
I’m pretty sure it 15cm
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Determine the values of the constants r and s such that i(x, y) = x rys is an integrating factor for the given differential equa

garri49 [273]

$\underbrace{y(7xy^2+6)}_{M(x,y)}\,\mathrm dx+\underbrace{x(xy^2-1)}_{N(x,y)}\,\mathrm dy=0$

For the ODE to be exact, we require that $M_y=N_x$ , which we'll verify is not the case here.

$M_y=21xy^2+6$
$N_x=2xy^2-1$

So we distribute an integrating factor $i(x,y)$ across both sides of the ODE to get

$iM\,\mathrm dx+iN\,\mathrm dy=0$

Now for the ODE to be exact, we require $(iM)_y=(iN)_x$ , which in turn means

$i_yM+iM_y=i_xN+iN_x\implies i(M_y-N_x)=i_xN-i_yM$

Suppose $i(x,y)=x^ry^s$ . Then substituting everything into the PDE above, we have

$x^ry^s(19xy^2+7)=rx^{r-1}y^s(x^2y^2-x)-sx^ry^{s-1}(7xy^3+6y)$
$19x^{r+1}y^{s+2}+7x^ry^s=rx^{r+1}y^{s+2}-rx^ry^s-7sx^{r+1}y^{s+2}-6sx^ry^s$
$19x^{r+1}y^{s+2}+7x^ry^s=(r-7s)x^{r+1}y^{s+2}-(r+6s)x^ry^s$
$\implies\begin{cases}r-7s=19\\r+6s=-7\end{cases}\implies r=5,s=-2$

so that our integrating factor is $i(x,y)=x^5y^{-2}$ . Our ODE is now

$(7x^6y+6x^5y^{-1})\,\mathrm dx+(x^7-x^6y^{-2})\,\mathrm dy=0$

Renaming $M(x,y)$ and $N(x,y)$ to our current coefficients, we end up with partial derivatives

$M_y=7x^6-6x^5y^{-2}$
$N_x=7x^6-6x^5y^{-2}$

as desired, so our new ODE is indeed exact.

Next, we're looking for a solution of the form $\Psi(x,y)=C$ . By the chain rule, we have

$\Psi_x=7x^6y+6x^5y^{-1}\implies\Psi=x^7y+x^6y^{-1}+f(y)$

Differentiating with respect to $y$ yields

$\Psi_y=x^7-x^6y^{-2}=x^7-x^6y^{-2}+\dfrac{\mathrm df}{\mathrm dy}$
$\implies\dfrac{\mathrm df}{\mathrm dy}=0\implies f(y)=C$

Thus the solution to the ODE is

$\Psi(x,y)=x^7y+x^6y^{-1}=C$

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3 years ago

What’s the simplified form of 2x+3-x+5

Natalija [7]

2x+3-x+5
x+8 is the simplified answer.

Hope this helps!!

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3 years ago

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Kelly has 4 times as many songs on her music player as Lou

jeka57 [31]

Answer:4 times x

4(x)

Step-by-step explanation:

4 times as many songs on Lou's music player

Lou's music player is x

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3 years ago

A cookie jar contains four oatmeal raisin, one sugar, nine chocolate chip, and six peanut butter cookies. If one is chosen at ra

Shtirlitz [24]

Answer:

chocolate chips

Step-by-step explanation:

The p denotes here the probability which is given below;

Given that

There is 4 oatmeal raisin

1 sugar

9 chocolate chips

And, 6 peanut butter cookies

So based on the above information, the probability when the one is chosen would be of chocolate chips as it contains the hight value in the cookie jar

So the same is to be selected

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2 years ago

100 POINTS PLEASE HURRY

Harlamova29_29 [7]

Answer:

5.80 to the power of 3. I would say this is the answer if you just look closely at the number line and you will see the answer

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