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3 years ago

The sum of a number, n, and 5 is subtracted from 8

Mathematics

1 answer:

siniylev [52]3 years ago

4 0

Answer:

i don't really understand ur question

8 - (n+5)

Step-by-step explanatio

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Lines ab and cd are parallel. If MN is 70° then what is my

fgiga [73]

The figure below is a parallelogram which statement must be true? D___________E | | |__________ | F G a.line Df is parallel to line de b. Line Df is parallel to line eg c. Line fg is parallel to line eg d. Line fg is parallel to line df 3. All __ are

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3 years ago

Y''+y'+y=0, y(0)=1, y'(0)=0

mars1129 [50]

Answer:

$y=e^{\frac{-t}{2}}\left ( \cos\left ( \frac{\sqrt{3}t}{2} \right )+\frac{1}{\sqrt{3}}\sin \left ( \frac{\sqrt{3}t}{2} \right ) \right )$

Step-by-step explanation:

A second order linear , homogeneous ordinary differential equation has form $ay''+by'+cy=0$ .

Given: $y''+y'+y=0$

Let $y=e^{rt}$ be it's solution.

We get,

$\left ( r^2+r+1 \right )e^{rt}=0$

Since $e^{rt}\neq 0$ , $r^2+r+1=0$

{ we know that for equation $ax^2+bx+c=0$ , roots are of form $x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$ }

We get,

$y=\frac{-1\pm \sqrt{1^2-4}}{2}=\frac{-1\pm \sqrt{3}i}{2}$

For two complex roots $r_1=\alpha +i\beta \,,\,r_2=\alpha -i\beta$ , the general solution is of form $y=e^{\alpha t}\left ( c_1\cos \beta t+c_2\sin \beta t \right )$

i.e $y=e^{\frac{-t}{2}}\left ( c_1\cos\left ( \frac{\sqrt{3}t}{2} \right )+c_2\sin \left ( \frac{\sqrt{3}t}{2} \right ) \right )$

Applying conditions y(0)=1 on $e^{\frac{-t}{2}}\left ( c_1\cos\left ( \frac{\sqrt{3}t}{2} \right )+c_2\sin \left ( \frac{\sqrt{3}t}{2} \right ) \right )$ , $c_1=1$

So, equation becomes $y=e^{\frac{-t}{2}}\left ( \cos\left ( \frac{\sqrt{3}t}{2} \right )+c_2\sin \left ( \frac{\sqrt{3}t}{2} \right ) \right )$

On differentiating with respect to t, we get

$y'=\frac{-1}{2}e^{\frac{-t}{2}}\left ( \cos\left ( \frac{\sqrt{3}t}{2} \right )+c_2\sin \left ( \frac{\sqrt{3}t}{2} \right ) \right )+e^{\frac{-t}{2}}\left ( \frac{-\sqrt{3}}{2} \sin \left ( \frac{\sqrt{3}t}{2} \right )+c_2\frac{\sqrt{3}}{2}\cos\left ( \frac{\sqrt{3}t}{2} \right )\right )$

Applying condition: y'(0)=0, we get $0=\frac{-1}{2}+\frac{\sqrt{3}}{2}c_2\Rightarrow c_2=\frac{1}{\sqrt{3}}$

Therefore,

$y=e^{\frac{-t}{2}}\left ( \cos\left ( \frac{\sqrt{3}t}{2} \right )+\frac{1}{\sqrt{3}}\sin \left ( \frac{\sqrt{3}t}{2} \right ) \right )$

3 0

3 years ago

(9 + 11) divided by (5 + 4 + 1) (9 + 11) write 3 steps then put the answer and i will give u brainliest!

Rufina [12.5K]

Answer:

(9 + 11) /(5 + 4 + 1)(9 + 11)

20/10(20)

20/200

1/10

4 0

3 years ago

Read 2 more answers

Add the equations 2x-3y=-1 + 3x+3y=26 A. 5x-6y=-27 B. 5x=27 C. 6y=25 D. 5x=25

jenyasd209 [6]

Answer:

D) 5x = 25

Step-by-step explanation:

-1+26 = 25

2x + 3x = 5x

-3y + 3y = 0

6 0

3 years ago

Read 2 more answers

Can anyone help me understand what a basic algebraic linear equation is, I'm struggling,

polet [3.4K]

A basic algebraic linear equation is just a fancy way of saying "equation of a line". They are most likely referring to the formula y=mx+b, where m is the slope and b in the y intercept. :)

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3 years ago