Please help — Which ratio represents cos(c)?

Simora [160]

From the homogeneous part of the ODE, we can get two fundamental solutions. The characteristic equation is

$3r^2-6r+6=0\iff r^2-2r+2=0$

which has roots at $r=1\pm i$ . This admits the two fundamental solutions

$y_1=e^x\cos x$
$y_2=e^x\sin x$

The particular solution is easiest to obtain via variation of parameters. We're looking for a solution of the form

$y_p=u_1y_1+u_2y_2$

where

$u_1=-\displaystyle\frac13\int\frac{y_2e^x\sec x}{W(y_1,y_2)}\,\mathrm dx$
$u_2=\displaystyle\frac13\int\frac{y_1e^x\sec x}{W(y_1,y_2)}\,\mathrm dx$

and $W(y_1,y_2)$ is the Wronskian of the fundamental solutions. We have

$W(e^x\cos x,e^x\sin x)=\begin{vmatrix}e^x\cos x&e^x\sin x\\e^x(\cos x-\sin x)&e^x(\cos x+\sin x)\end{vmatrix}=e^{2x}$

and so

$u_1=-\displaystyle\frac13\int\frac{e^{2x}\sin x\sec x}{e^{2x}}\,\mathrm dx=-\int\tan x\,\mathrm dx$
$u_1=\dfrac13\ln|\cos x|$

$u_2=\displaystyle\frac13\int\frac{e^{2x}\cos x\sec x}{e^{2x}}\,\mathrm dx=\int\mathrm dx$
$u_2=\dfrac13x$

Therefore the particular solution is

$y_p=\dfrac13e^x\cos x\ln|\cos x|+\dfrac13xe^x\sin x$

so that the general solution to the ODE is

$y=C_1e^x\cos x+C_2e^x\sin x+\dfrac13e^x\cos x\ln|\cos x|+\dfrac13xe^x\sin x$

7 0

3 years ago

a certain shade of blue is made by mixing 1.5 quarts of blue paint with 5 quarts of white paint. If you need a total of 16.25 ga

Law Incorporation [45]

we know the blue and white paints are on a 1.5 : 5 ratio, thus, if we have a total of 16.25 gallons of paint to be split along that ratio, we can simply divide 16.25 by (1.5+5) and distribute accordingly.

$\bf \cfrac{blue}{white}\qquad \stackrel{ratio}{1.5:5}\qquad \cfrac{1.5}{5}~\hspace{5em}\cfrac{1.5\cdot \frac{16.25}{1.5+5}}{5\cdot \frac{16.25}{1.5+5}}\implies \cfrac{1.5\cdot \frac{16.25}{6.5}}{5\cdot \frac{16.25}{6.5}} \\\\\\ \cfrac{1.5\cdot 2.5}{5\cdot 2.5}\implies \cfrac{3.75}{12.5}\qquad \qquad \boxed{\stackrel{blue}{3.75}~:~\stackrel{white}{12.5}}$

5 0

3 years ago

Can someone explain to me in words how to do this problem 3x+122=22x-11

inn [45]

When you have this type of problem, you need to combine the like-terms and isolate the variable.

3x + 122 = 22x - 11

Add 11 to both sides to get rid of it

3x + 122 + 11 = 22x - 11 + 11 (-11 + 11=0)

3x + 133 = 22x

Then you would bring the 3x to the other side, so subtract 3x from both sides

3x + 133 = 22x

-3x -3x

133 = 22x - 3x

133 = 19x

Then divide both sides by 19 to isolate x

133/19 = 19x/19

133/19 = 7, so x = 7

Hope this helps!!

8 0

2 years ago

1 2 3 4 5 6 7 8 9 10

kirza4 [7]

Yes so i do need to doing the times and multipics then get a fraction then u will get tot eh answer

6 0

3 years ago

Hannah earned $1536 in 8 years on an investment at a 4% annual simple interest rate. How much was Hannah’s investment? $4800 $30

Nonamiya [84]

Simple interest calculates interest on initial amount only. The investment by Hannah was : Option A: $4800

<h3>How to calculate simple interest amount if rate of interest is R% annually?</h3>

Suppose that the initial amount of investment is P

And the rate of simple interest is R% annually,

And the time of investment is T years.

Then, the amount of simple interest is calculated as:

$I = \dfrac{P \times R \times T}{100}$

For the given case, let the initial investment Hannah made was of $P

Then, the time of investment is T = 8 years, R% = 4%, and given that Hannah earned interest I = $1536

Putting values in the above formula, we get;

$I = \dfrac{P \times R \times T}{100}\\\\1536 = \dfrac{P \times 8 \times 4}{100}\\\\P = \dfrac{153600}{32} = 4800$

Thus,

The investment by Hannah was : Option A: $4800

Learn more about simple interest here:

brainly.com/question/5319581

5 0

2 years ago