PLS HELP WILL GIVE BRAINLIEST

Chris has 115$ to spend at a shopping mall . If he decides to spend $42 on clothing and $37 on food how much money will he have

Katena32 [7]

Answer:

$36 left

Step-by-step explanation:

42+37=79

115-79=36

7 0

2 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

2 years ago

HELP IM FAILING MATH I NEED HELP :(

CaHeK987 [17]

Answer:idk

Step-by-step explanation:

idk

7 0

3 years ago

Read 2 more answers

Axis of symmetry y=x^2-4x+1

Andrei [34K]

Answer:

So for a quadratic function, the axis of symmetry is the line that divides the curved line in the middle, which is the h value, it can be found by using the formula -b/2a, so for here it would be 4/2(1) = 2, so x =2

Hope that answers your question

Step-by-step explanation:

6 0

1 year ago

Two mechanics worked on a car. The first mechanic charged S95 per hour, and the second mechanic charged $115 per hour.

natima [27]

Answer:

First mechanic worked for 10 hours and second mechanic worked for 15 hours.

Step-by-step explanation:

Let first mechanic worked for X hours and second mechanic worked for Y hours .

Now, according to the question , they worked for a total of 25 hours .

Thus ,

X + Y = 25.

Y = 25 - X -(1)

Also, first mechanic is charging $ 95 per hour and second mechanic is charging $115 per hour .

Thus, total money charged by them will be 95X + 115Y .

Which is given to be $2675 in the question.

Thus 95X + 115Y = 2675. -(2)

Putting equation 1 in equation 2 we get ,

95X + 2875 - 115X = 2675

20X = 200

X = 10 hours.

Thus , Y = 25 - X = 15 hours.

Thus first mechanic worked for 10 hours and second mechanic worked for 15 hours.

5 0

2 years ago