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3 years ago

13

kittens weigh about 100 grams when born and gain 7 to 15 grams per day. If a kitten weighs 100 grams at birth and gained 8 grams

per day, in how many days will the kitten triple its weight?

1 answer:

scoray [572]3 years ago

8 0

After 25 days. 300=triple 100+8x=300. is that 20 words?

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a food bank has 50 cans of vegetables 30 loaves of bread and 100 bottles of water. The volunteers will put the items into boxes.

olchik [2.2K]

10 boxes with 5 cans of vegetables,6 boxes with 5 loaves of bread and 20 boxes with 5 bottles of water.

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

2 years ago

Patsy can decorate 3 1/2 cakes in 1/4 hour. At this rate, how many cakes can she decorate in 1 hour?

nika2105 [10]

The answer is 14 because 3 1/2 multiplied by 4 is 14. Hope this helps

7 0

3 years ago

I just need to know what's Nine sixty-eight thousand one hundred twenty-three

schepotkina [342]

Answer:

98,123

Step-by-step explanation:

3 0

3 years ago

Read 2 more answers

Jean can pack 5 cartons in 15 minutes. Which expression can be used to show the number of cartons Jean can pack in x hours? Grou

nadezda [96]

Answer: 20x

Step-by-step explanation:

First we should note that 60 minutes = 1 hour. Therefore, 15 minutes = 15/60 = 1/4 hour

Since Jean can pack 5 cartons in 1/4 hours, the number of carton that he can pack in one hour will be:

= 5 ÷ 1/4

= 5 × 4

= 20 cartons.

Therefore, to get the number of cartons that Jean can pack in x hours, we will multiply 20 by x. This will be:

= 20 × x

= 20x

6 0

2 years ago