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3 years ago

6

an average speed of 57 km/h and the remaining 55 km at an average speed of 110 km/h. Find the average speed of the car for its e

ntire journey.

1 answer:

MrMuchimi3 years ago

6 0

Answer:

83.5km/h

Step-by-step explanation:

To find average you have to add up all the numbers in a given set then divide it by the amount of numbers in that set

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Evaluate the factorial expression.<br> left parenthesis 6 minus 2 right parenthesis exclamation mark

kondaur [170]

If I understood your post correctly, then this will be the equation we evaluate: (6-2)!

We can simplify this to: 4!

4! = 4 x 3 x 2 x 1 = 24

4 0

3 years ago

Use green's theorem to compute the area inside the ellipse x252+y2172=1. use the fact that the area can be written as ∬ddxdy=12∫

Pavel [41]

The area of the ellipse $E$ is given by

$\displaystyle\iint_E\mathrm dA=\iint_E\mathrm dx\,\mathrm dy$

To use Green's theorem, which says

$\displaystyle\int_{\partial E}L\,\mathrm dx+M\,\mathrm dy=\iint_E\left(\frac{\partial M}{\partial x}-\frac{\partial L}{\partial y}\right)\,\mathrm dx\,\mathrm dy$

( $\partial E$ denotes the boundary of $E$ ), we want to find $M(x,y)$ and $L(x,y)$ such that

$\dfrac{\partial M}{\partial x}-\dfrac{\partial L}{\partial y}=1$

and then we would simply compute the line integral. As the hint suggests, we can pick

$\begin{cases}M(x,y)=\dfrac x2\\\\L(x,y)=-\dfrac y2\end{cases}\implies\begin{cases}\dfrac{\partial M}{\partial x}=\dfrac12\\\\\dfrac{\partial L}{\partial y}=-\dfrac12\end{cases}\implies\dfrac{\partial M}{\partial x}-\dfrac{\partial L}{\partial y}=1$

The line integral is then

$\displaystyle\frac12\int_{\partial E}-y\,\mathrm dx+x\,\mathrm dy$

We parameterize the boundary by

$\begin{cases}x(t)=5\cos t\\y(t)=17\sin t\end{cases}$

with $0\le t\le2\pi$ . Then the integral is

$\displaystyle\frac12\int_0^{2\pi}(-17\sin t(-5\sin t)+5\cos t(17\cos t))\,\mathrm dt$

$=\displaystyle\frac{85}2\int_0^{2\pi}\sin^2t+\cos^2t\,\mathrm dt=\frac{85}2\int_0^{2\pi}\mathrm dt=85\pi$

###

Notice that $x^{2/3}+y^{2/3}=4^{2/3}$ kind of resembles the equation for a circle with radius 4, $x^2+y^2=4^2$ . We can change coordinates to what you might call "pseudo-polar":

$\begin{cases}x(t)=4\cos^3t\\y(t)=4\sin^3t\end{cases}$

which gives

$x(t)^{2/3}+y(t)^{2/3}=(4\cos^3t)^{2/3}+(4\sin^3t)^{2/3}=4^{2/3}(\cos^2t+\sin^2t)=4^{2/3}$

as needed. Then with $0\le t\le2\pi$ , we compute the area via Green's theorem using the same setup as before:

$\displaystyle\iint_E\mathrm dx\,\mathrm dy=\frac12\int_0^{2\pi}(-4\sin^3t(12\cos^2t(-\sin t))+4\cos^3t(12\sin^2t\cos t))\,\mathrm dt$

$=\displaystyle24\int_0^{2\pi}(\sin^4t\cos^2t+\cos^4t\sin^2t)\,\mathrm dt$

$=\displaystyle24\int_0^{2\pi}\sin^2t\cos^2t\,\mathrm dt$

$=\displaystyle6\int_0^{2\pi}(1-\cos2t)(1+\cos2t)\,\mathrm dt$

$=\displaystyle6\int_0^{2\pi}(1-\cos^22t)\,\mathrm dt$

$=\displaystyle3\int_0^{2\pi}(1-\cos4t)\,\mathrm dt=6\pi$

3 0

3 years ago

Depending on the car and the additional features, a convertible sports car can cost between $19,028 and $370,790. Write two ineq

liraira [26]

Cost of Car= C

$19,028 <span>≥</span><span> C ≤ $370,790
</span>
The cost of the sports car is greater than or equal to $19, 028 and less than or equal to $370,790.

6 0

3 years ago

Two cars leave from a town at the same time traveling in opposite directions. One travels 5 mph faster than the other. In 3 hour

Doss [256]

Let the slower cars speed equal X.

The faster cars speed would be X+5 ( 5 mph faster).

They traveled for 3 hours

Multiply the time of travel by speed to equal the number of miles traveled.

So you have:

3X + 3(X+5) = 267 miles

Simplify the left side:

3X + 3X+15 = 267

Combine like terms:

6x + 15 = 267

Subtract 15 from each side"

6x = 252

Divide each side by 6:

x = 252 / 6

X = 42

The slower car was traveling at 42 mph and the faster car was traveling at 47 mph.

7 0

3 years ago

Nancy's Cupcakes recorded how many cupcakes it recently sold of each flavor.

Alexeev081 [22]

Answer:

pumpkin because it got the most sold

7 0

3 years ago