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3 years ago

6. Emma uses 10 pages of paper when she writes anything. She uses an

Mathematics

1 answer:

Savatey [412]3 years ago

6 0

Answer:

4x+10

Step-by-step explanation:

Emma is guaranteed to use 10 pages when she writes something. Since you can't tell how many hours she has written, you use x to represent the hours she has spent writing. If she writes 4 pages every hour, that would be 4 × (hours spent writing) or 4x. Add 4x to the original guaranteed 10 pages she uses and you have your expression.

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Evaluate the integral e^xy w region d xy=1, xy=4, x/y=1, x/y=2

LUCKY_DIMON [66]

Make a change of coordinates:

$u(x,y)=xy$
$v(x,y)=\dfrac xy$

The Jacobian for this transformation is

$\mathbf J=\begin{bmatrix}\dfrac{\partial u}{\partial x}&\dfrac{\partial v}{\partial x}\\\\\dfrac{\partial u}{\partial y}&\dfrac{\partial v}{\partial y}\end{bmatrix}=\begin{bmatrix}y&x\\\\\dfrac1y&-\dfrac x{y^2}\end{bmatrix}$

and has a determinant of

$\det\mathbf J=-\dfrac{2x}y$

Note that we need to use the Jacobian in the other direction; that is, we've computed

$\mathbf J=\dfrac{\partial(u,v)}{\partial(x,y)}$

but we need the Jacobian determinant for the reverse transformation (from $(x,y)$ to $(u,v)$ . To do this, notice that

$\dfrac{\partial(x,y)}{\partial(u,v)}=\dfrac1{\dfrac{\partial(u,v)}{\partial(x,y)}}=\dfrac1{\mathbf J}$

we need to take the reciprocal of the Jacobian above.

The integral then changes to

$\displaystyle\iint_{\mathcal W_{(x,y)}}e^{xy}\,\mathrm dx\,\mathrm dy=\iint_{\mathcal W_{(u,v)}}\dfrac{e^u}{|\det\mathbf J|}\,\mathrm du\,\mathrm dv$
$=\displaystyle\frac12\int_{v=}^{v=}\int_{u=}^{u=}\frac{e^u}v\,\mathrm du\,\mathrm dv=\frac{(e^4-e)\ln2}2$

8 0

3 years ago

Need help with a simple problem 2^x=3^x+1

KiRa [710]

For $x\ \textgreater \ 0$ , $2^x\ \textless \ 3^x$ , all the more $2^x\ \textless \ 3^x+1$ , therefore no solution.

For $x=0$ , we have $2^0=3^0+1 \Rightarrow 1=1+1 \Rightarrow 1=2$ . Obviously that' false.

For $x\ \textless \ 0$ both $2^x$ and $3^x$ , where $2^x\ \textgreater \ 3^x$ , belong to the range $(0,1)$ , then $3^x+1$ belong to the range $(1,2)$ .
Those ranges don't have a common part, therefore, again, no solution.

So, the equation $2^x=3^x+1$ doesn't have a solution.

4 0

3 years ago

Please hurry i need help

kirza4 [7]

Answer:

(x^2+16x+63)

Step-by-step explanation:

(x^2+17x+72)-(1x+9)

(x^2+16x+63)

If this is incorrect I appologize

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3 years ago

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HELPPP FOR BRAINLEST!!! RIGHT NOW PLEASE

satela [25.4K]

Answer:

1st is correct

Step-by-step explanation:

Like charges repel each other.

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3 0

2 years ago

What is 16-2k=14? somebody help pls

mina [271]

Answer:

K=1

Step-by-step explanation:

1 times 2 equals 2

16-2 equals 14

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3 years ago

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